コグノスケ

QEMU Spikeモード用のシリアルドライバ実装

/*
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @brief UART driver for the Spike Simulator
 */

#include <kernel.h>
#include <arch/cpu.h>
#include <drivers/uart.h>

volatile u64_t tohost;
volatile u64_t fromhost;

void uart_spike_poll_out(struct device *dev, unsigned char c)
{
        u64_t cmd;

        // QEMU spike mode
        u8_t dev_no = 1;
        u8_t cmd_no = 1;
        u64_t payload = c;

        cmd = ((u64_t)dev_no << 56) |
                ((u64_t)cmd_no << 48) |
                (payload & 0xffffffffffffULL);

        tohost = cmd;

        while (fromhost == 0)
                ;
        fromhost = 0;
}

static int uart_spike_poll_in(struct device *dev, unsigned char *c)
{
        return -1;
}

static int uart_spike_init(struct device *dev)
{
        return 0;
}

static const struct uart_driver_api uart_spike_driver_api = {
        .poll_in          = uart_spike_poll_in,
        .poll_out         = uart_spike_poll_out,
};

DEVICE_AND_API_INIT(uart_spike_0, DT_INST_0_SPIKE_UART_SPIKE_LABEL,
                    uart_spike_init, NULL, NULL,
                    PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
                    (void *)&uart_spike_driver_api);

ラベルが未定義のエラー

zephyr/drivers/serial/uart_spike.c:73:35: error: 'DT_INST_0_SPIKE_UART_SPIKE_LABEL' undeclared here (not in a function); did you mean 'DT_COMPAT_SPIKE_UART_SPIKE'?
 DEVICE_AND_API_INIT(uart_spike_0, DT_INST_0_SPIKE_UART_SPIKE_LABEL,
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../include/device.h:106:11: note: in definition of macro 'DEVICE_AND_API_INIT'
   .name = drv_name, .init = (init_fn),     \
           ^~~~~~~~
[89/97] Linking C static library zephyr/libzephyr.a
ninja: build stopped: subcommand failed.

QEMU Spikeモードの文字出力

// https://github.com/qemu/qemu/blob/master/hw/riscv/riscv_htif.c

...

static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written)
{
    uint8_t device = val_written >> 56;
    uint8_t cmd = val_written >> 48;
    uint64_t payload = val_written & 0xFFFFFFFFFFFFULL;
    int resp = 0;

...

    } else if (likely(device == 0x1)) {
        /* HTIF Console */
        if (cmd == 0x0) {
            /* this should be a queue, but not yet implemented as such */
            htifstate->pending_read = val_written;
            htifstate->env->mtohost = 0; /* clear to indicate we read */
            return;
        } else if (cmd == 0x1) {
            qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1);
            resp = 0x100 | (uint8_t)payload;
        } else {
            qemu_log("HTIF device %d: unknown command\n", device);
        }
    } else {

...

    htifstate->env->mfromhost = (val_written >> 48 << 48) | (resp << 16 >> 16);
    htifstate->env->mtohost = 0; /* clear to indicate we read */
}

zephyr/dts/bindings/serial/spike,uart-spike.yaml

# SPDX-License-Identifier: Apache-2.0

description: UART for Spike Simulator

compatible: "spike,uart-spike"

include: uart-controller.yaml

QEMU SpikeモードでHello world

$ /usr/bin/qemu-system-riscv32 -nographic -machine spike -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel zephyr/build/zephyr/zephyr.elf

qemu-system-riscv32: clint: time_hi write not implemented
qemu-system-riscv32: clint: time_lo write not implemented
qemu-system-riscv32: clint: time_hi write not implemented
*** Booting Zephyr OS build zephyr-v2.1.0-1699-gbb40304f2531  ***
Hello World! hoge

zephyr/drivers/serial/Kconfig.spike

# SPDX-License-Identifier: Apache-2.0

menuconfig UART_SPIKE
        bool "Spike Simulator serial driver"
        depends on SOC_RISCV_SPIKE
        select SERIAL_HAS_DRIVER
        help
          This option enables the Spike Simulator serial driver.

zephyr/drivers/serial/Kconfigに追加する行

...

source "drivers/serial/Kconfig.litex"

source "drivers/serial/Kconfig.rtt"

source "drivers/serial/Kconfig.xlnx"

source "drivers/serial/Kconfig.spike"    # ★この行を足す★

endif # SERIAL

Kconfig追加後のcmake

-- Configuring done
CMake Error at ../../cmake/extensions.cmake:372 (add_library):
  No SOURCES given to target: drivers__serial
Call Stack (most recent call first):
  ../../cmake/extensions.cmake:349 (zephyr_library_named)
  ../../drivers/serial/CMakeLists.txt:3 (zephyr_library)


CMake Generate step failed.  Build files cannot be regenerated correctly.
FAILED: build.ninja

zephyr/drivers/serial/CMakeLists.txtに追加する行

...

zephyr_library_sources_if_kconfig(uart_liteuart.c)
zephyr_library_sources_ifdef(CONFIG_UART_RTT_DRIVER uart_rtt.c)
zephyr_library_sources_if_kconfig(uart_xlnx_ps.c)
zephyr_library_sources_if_kconfig(uart_spike.c)    # ★この行を足す★

...

zephyr_library_sources_if_kconfigの実装

# zephyr/cmake/extensions.cmake

...

# zephyr_library_sources_if_kconfig(fft.c)
# is the same as
# zephyr_library_sources_ifdef(CONFIG_FFT fft.c)

...

function(zephyr_library_sources_if_kconfig item)
  get_filename_component(item_basename ${item} NAME_WE)
  string(TOUPPER CONFIG_${item_basename} UPPER_CASE_CONFIG)
  zephyr_library_sources_ifdef(${UPPER_CASE_CONFIG} ${item})
endfunction()

...

function(zephyr_library_sources_ifdef feature_toggle source)
  if(${${feature_toggle}})
    zephyr_library_sources(${source} ${ARGN})
  endif()
endfunction()


# zephyr/cmake/extensions.cmake

...

function(zephyr_library_sources source)
  target_sources(${ZEPHYR_CURRENT_LIBRARY} PRIVATE ${source} ${ARGN})
endfunction()

...

最初のninja実行結果

In file included from ../include/arch/cpu.h:25,
                 from ../include/kernel_includes.h:34,
                 from ../include/kernel.h:17,
                 from zephyr/arch/riscv/core/offsets/offsets.c:16:
../include/arch/riscv/arch.h:25:10: fatal error: soc.h: No such file or directory
 #include <soc.h>
          ^~~~~~~
compilation terminated.
ninja: build stopped: subcommand failed.

zephyr/soc/riscv/riscv-privilege/spike/soc.h

/*
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file SoC configuration macros for the Spike series processor
 */

#ifndef __RISCV_SPIKE_SOC_H_
#define __RISCV_SPIKE_SOC_H_

#include <soc_common.h>
#include <devicetree.h>

#endif /* __RISCV_SPIKE_SOC_H_ */

soc.h追加後のninja実行結果

zephyr/drivers/interrupt_controller/intc_plic.c: In function 'riscv_plic_irq_enable':
zephyr/drivers/interrupt_controller/intc_plic.c:45:41: error: 'DT_PLIC_IRQ_EN' undeclared (first use in this function); did you mean 'PLIC_IRQS'?
  volatile u32_t *en = (volatile u32_t *)DT_PLIC_IRQ_EN;
                                         ^~~~~~~~~~~~~~
                                         PLIC_IRQS

soc.h追加後のninja実行結果

zephyr/drivers/timer/riscv_machine_timer.c: In function 'set_mtimecmp':
zephyr/drivers/timer/riscv_machine_timer.c:28:31: error: 'RISCV_MTIMECMP_BASE' undeclared (first use in this function)
  volatile u32_t *r = (u32_t *)RISCV_MTIMECMP_BASE;
                               ^~~~~~~~~~~~~~~~~~~
zephyr/drivers/timer/riscv_machine_timer.c:28:31: note: each undeclared identifier is reported only once for each function it appears in
zephyr/drivers/timer/riscv_machine_timer.c: In function 'mtime':
zephyr/drivers/timer/riscv_machine_timer.c:47:31: error: 'RISCV_MTIME_BASE' undeclared (first use in this function)
  volatile u32_t *r = (u32_t *)RISCV_MTIME_BASE;
                               ^~~~~~~~~~~~~~~~
[87/94] Linking C static library zephyr/kernel/libkernel.a
ninja: build stopped: subcommand failed.

QEMUのSpike, CLINT関連のソースコード

// https://github.com/qemu/qemu/blob/master/hw/riscv/spike.c

static const struct MemmapEntry {
    hwaddr base;
    hwaddr size;
} spike_memmap[] = {
    [SPIKE_MROM] =     {     0x1000,    0x11000 },
    [SPIKE_CLINT] =    {  0x2000000,    0x10000 },
    [SPIKE_DRAM] =     { 0x80000000,        0x0 },
};


// https://github.com/qemu/qemu/blob/master/include/hw/riscv/sifive_clint.h

enum {
    SIFIVE_SIP_BASE     = 0x0,
    SIFIVE_TIMECMP_BASE = 0x4000,
    SIFIVE_TIME_BASE    = 0xBFF8
};

zephyr/soc/riscv/riscv-privilege/spike/soc.hに追記する内容

/* Timer configuration */
#define RISCV_MTIMECMP_BASE          0x02004000
#define RISCV_MTIME_BASE             0x0200bff8

ビルド成功

$ ninja

[0/1] Re-running CMake...
-- Zephyr version: 2.1.99
-- Selected BOARD hoge
-- Loading zephyr/boards/riscv/hoge/hoge.dts as base
hoge.dts.pre.tmp:22.17-25.5: Warning (simple_bus_reg): /soc/serial: missing or empty reg/ranges property
  also defined at hoge.dts.pre.tmp:37.8-39.3
Devicetree header saved to 'zephyr/build/zephyr/include/generated/devicetree_unfixed.h'
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/build/zephyr/.config'
No change to configuration in 'zephyr/build/zephyr/.config'
No change to Kconfig header in 'zephyr/build/zephyr/include/generated/autoconf.h'
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build
[89/94] Linking C executable zephyr/zephyr_prebuilt.elf
Memory region         Used Size  Region Size  %age Used
             RAM:       12752 B        16 KB     77.83%
        IDT_LIST:          25 B         2 KB      1.22%
[94/94] Linking C executable zephyr/zephyr.elf

実行しても何も表示されない

$ /usr/bin/qemu-system-riscv32 -nographic -machine spike -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel zephyr/build/zephyr/zephyr.elf

qemu-system-riscv32: clint: time_hi write not implemented
qemu-system-riscv32: clint: time_lo write not implemented
qemu-system-riscv32: clint: time_hi write not implemented

main関数まで到達しているようだ

$ riscv64-zephyr-elf-gdb zephyr/build/zephyr/zephyr.elf

GNU gdb (crosstool-NG 1.24.0.60-a152d61) 8.3.1
Copyright (C) 2019 Free Software Foundation, Inc.

...

(gdb) target remote localhost:1234

Remote debugging using localhost:1234
0x00001000 in ?? ()


(gdb) b main

Breakpoint 1 at 0x800006d4: file zephyr/samples/hello_world/src/main.c, line 12.


(gdb) c

Continuing.

Breakpoint 1, main ()
    at zephyr/samples/hello_world/src/main.c:12
12              printk("Hello World! %s
", CONFIG_BOARD);

hoge.dtsを変更してcmakeしたときのエラー

warning: UART_CONSOLE (defined at drivers/console/Kconfig:47) was assigned the value 'y' but got the
value 'n'. Check these unsatisfied dependencies: SERIAL_HAS_DRIVER (=n). See
http://docs.zephyrproject.org/latest/reference/kconfig/CONFIG_UART_CONSOLE.html and/or look up
UART_CONSOLE in the menuconfig/guiconfig interface. The Application Development Primer, Setting
Configuration Values, and Kconfig - Tips and Best Practices sections of the manual might be helpful
too.


warning: RISCV_MACHINE_TIMER (defined at drivers/timer/Kconfig:153) was assigned the value 'y' but
got the value 'n'. Check these unsatisfied dependencies: SOC_FAMILY_RISCV_PRIVILEGE (=n). See
http://docs.zephyrproject.org/latest/reference/kconfig/CONFIG_RISCV_MACHINE_TIMER.html and/or look
up RISCV_MACHINE_TIMER in the menuconfig/guiconfig interface. The Application Development Primer,
Setting Configuration Values, and Kconfig - Tips and Best Practices sections of the manual might be
helpful too.


warning: The choice symbol BOARD_HOGE (defined at boards/riscv/hoge/Kconfig.board:3) was selected
(set =y), but no symbol ended up as the choice selection. See
http://docs.zephyrproject.org/latest/reference/kconfig/CONFIG_BOARD_HOGE.html and/or look up
BOARD_HOGE in the menuconfig/guiconfig interface. The Application Development Primer, Setting
Configuration Values, and Kconfig - Tips and Best Practices sections of the manual might be helpful
too.


zephyr/boards/riscv/hoge/hoge_defconfig:4: warning: attempt to assign the value 'y' to the undefined symbol SOC_SERIES_RISCV_SPIKE

zephyr/boards/riscv/hoge/hoge_defconfig:5: warning: attempt to assign the value 'y' to the undefined symbol SOC_RISCV_SPIKE

error: Aborting due to Kconfig warnings

CMake Error at zephyr/cmake/kconfig.cmake:216 (message):
  command failed with return code: 1
Call Stack (most recent call first):
  zephyr/cmake/app/boilerplate.cmake:461 (include)
  CMakeLists.txt:5 (include)

hoge_defconfigからSiFive用の設定を削る

diff --git a/boards/riscv/hoge/hoge_defconfig b/boards/riscv/hoge/hoge_defconfig
index 3f9626815f..32c4e9e90d 100644
--- a/boards/riscv/hoge/hoge_defconfig
+++ b/boards/riscv/hoge/hoge_defconfig
@@ -1,19 +1,12 @@
 # SPDX-License-Identifier: Apache-2.0
 
 CONFIG_RISCV=y
-CONFIG_SOC_SERIES_RISCV_SIFIVE_FREEDOM=y
-CONFIG_SOC_RISCV_SIFIVE_FREEDOM=y
+CONFIG_SOC_SERIES_RISCV_SPIKE=y
+CONFIG_SOC_RISCV_SPIKE=y
 CONFIG_BOARD_HOGE=y
 CONFIG_CONSOLE=y
 CONFIG_PRINTK=y
 CONFIG_SERIAL=y
-CONFIG_UART_SIFIVE=y
-CONFIG_UART_SIFIVE_PORT_0=y
 CONFIG_UART_CONSOLE=y
-CONFIG_PLIC=y
-CONFIG_PINMUX=y
-CONFIG_PINMUX_SIFIVE=y
 CONFIG_RISCV_MACHINE_TIMER=y
-CONFIG_GPIO=y
-CONFIG_GPIO_SIFIVE=y
 CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=10000000

Kconfigの依存関係

# zephyr/soc/Kconfig

  source "$(SOC_DIR)/$(ARCH)/*/Kconfig.soc"


# zephyr/soc/riscv/riscv-privilege/Kconfig.soc

  source "soc/riscv/riscv-privilege/*/Kconfig.series"

zephyr/soc/riscv/riscv-privilege/spike/Kconfig.series

# RISCV_SPIKE SOC implementation

# SPDX-License-Identifier: Apache-2.0

config SOC_SERIES_RISCV_SPIKE
        bool "SPIKE series SOC implementation"
        depends on RISCV
        select SOC_FAMILY_RISCV_PRIVILEGE
        help
          Enable support for Spike series SOC

RISC-V PrivilegedのKconfig依存関係（再整理）

# zephyr/Kconfig

  source "Kconfig.zephyr"


# zephyr/Kconfig.zephyr

  source "$(SOC_DIR)/Kconfig"    # SOC_DIR = soc


# zephyr/soc/Kconfig

  choice
  	prompt "SoC/CPU/Configuration Selection"

  source "$(SOC_DIR)/$(ARCH)/*/Kconfig.soc"    # soc/riscv/riscv-privilege/Kconfig.soc

  endchoice

  menu "Hardware Configuration"
  osource "$(SOC_DIR)/$(ARCH)/Kconfig"
  osource "$(SOC_DIR)/$(ARCH)/*/Kconfig"    # soc/riscv/riscv-privilege/Kconfig


# zephyr/soc/riscv/riscv-privilege/Kconfig.soc

  source "soc/riscv/riscv-privilege/*/Kconfig.series"


# zephyr/soc/riscv/riscv-privilege/Kconfig

  config SOC_FAMILY_RISCV_PRIVILEGE    # riscv-privilege/spike/Kconfig.seriesのselectで有効にする
  config SOC_FAMILY
  config RISCV_HAS_PLIC

  ...

  source "soc/riscv/riscv-privilege/*/Kconfig.soc"

zephyr/soc/riscv/riscv-privilege/spike/Kconfig.soc

# RISCV_SPIKE SOC configuration options

# SPDX-License-Identifier: Apache-2.0

choice
        prompt "Spike series SOC implementation"
        depends on SOC_SERIES_RISCV_SPIKE

config SOC_RISCV_SPIKE
        bool "Spike SOC implementation"
        select ATOMIC_OPERATIONS_C

endchoice

アトミック演算の定義箇所

//zephyr/include/sys/atomic.h

#ifdef CONFIG_ATOMIC_OPERATIONS_BUILTIN
static inline bool atomic_cas(atomic_t *target, atomic_val_t old_value,
                          atomic_val_t new_value)
{
        return __atomic_compare_exchange_n(target, &old_value, new_value,
                                           0, __ATOMIC_SEQ_CST,
                                           __ATOMIC_SEQ_CST);
}
#elif defined(CONFIG_ATOMIC_OPERATIONS_C)
__syscall int atomic_cas(atomic_t *target, atomic_val_t old_value,
                         atomic_val_t new_value);

#else
extern int atomic_cas(atomic_t *target, atomic_val_t old_value,
                      atomic_val_t new_value);
#endif

Kconfig追加後のcmakeのエラー

CMake Error at ../../CMakeLists.txt:372 (message):
  Could not find linker script:
  'zephyr/soc/riscv//linker.ld'.
  Corrupted configuration?

cmakeがlinker.ldを探している箇所

# zephyr/CMakeLists.txt

...

if(CONFIG_HAVE_CUSTOM_LINKER_SCRIPT)
  set(LINKER_SCRIPT ${APPLICATION_SOURCE_DIR}/${CONFIG_CUSTOM_LINKER_SCRIPT})
  if(NOT EXISTS ${LINKER_SCRIPT})
    set(LINKER_SCRIPT ${CONFIG_CUSTOM_LINKER_SCRIPT})
    assert_exists(CONFIG_CUSTOM_LINKER_SCRIPT)
  endif()
else()
  # Try a board specific linker file
  set(LINKER_SCRIPT ${BOARD_DIR}/linker.ld)    # ★★★これ、もしくは★★★
  if(NOT EXISTS ${LINKER_SCRIPT})
    # If not available, try an SoC specific linker file
    set(LINKER_SCRIPT ${SOC_DIR}/${ARCH}/${SOC_PATH}/linker.ld)    # ★★★これ★★★
  endif()
endif()

if(NOT EXISTS ${LINKER_SCRIPT})
  message(FATAL_ERROR "Could not find linker script: '${LINKER_SCRIPT}'. Corrupted configuration?")
endif()

cmakeがSOC_PATHを決める箇所

# zephyr/cmake/app/boilerplate.cmake

...

set(SOC_NAME   ${CONFIG_SOC})
set(SOC_SERIES ${CONFIG_SOC_SERIES})
set(SOC_FAMILY ${CONFIG_SOC_FAMILY})

if("${SOC_SERIES}" STREQUAL "")
  set(SOC_PATH ${SOC_NAME})
else()
  set(SOC_PATH ${SOC_FAMILY}/${SOC_SERIES})
endif()

CONFIG_SOC_SERIESの定義箇所

$ cd zephyr/soc/riscv/riscv-privilege
$ grep -r 'config SOC_SERIES'

miv/Kconfig.defconfig.series:config SOC_SERIES
miv/Kconfig.series:config SOC_SERIES_RISCV32_MIV
sifive-freedom/Kconfig.defconfig.series:config SOC_SERIES
sifive-freedom/Kconfig.series:config SOC_SERIES_RISCV_SIFIVE_FREEDOM

Kconfig.defconfig.seriesの依存関係

# zephyr/Kconfig

  source "Kconfig.zephyr"

# zephyr/Kconfig.zephyr

  source "$(SOC_DIR)/$(ARCH)/*/Kconfig.defconfig"    # SOC_DIR = soc, ARCH = riscv


# zephyr/soc/riscv/riscv-privilege/Kconfig.defconfig

  source "soc/riscv/riscv-privilege/*/Kconfig.defconfig.series"

zephyr/soc/riscv/riscv-privilege/spike/Kconfig.defconfig.series

# SPDX-License-Identifier: Apache-2.0

if SOC_SERIES_RISCV_SPIKE

config SOC_SERIES
        default "spike"

config RISCV_HAS_PLIC
        default n

config NUM_IRQS
        default 16

config XIP
        default n

endif #SOC_SERIES_RISCV_SPIKE

zephyr/soc/riscv/riscv-privilege/spike/linker.ld

/*
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @brief Linker script for the Spike series processor
 */

#include <arch/riscv/common/linker.ld>

cmake最後のエラー

CMake Error at ../../soc/riscv/riscv-privilege/CMakeLists.txt:4 (add_subdirectory):
  The source directory

    /home/katsuhiro/share/projects/oss/zephyr/soc/riscv/riscv-privilege/spike

  does not contain a CMakeLists.txt file.


-- Configuring incomplete, errors occurred!

zephyr/soc/riscv/riscv-privilege/spike/CMakeLists.txt

# SPDX-License-Identifier: Apache-2.0

zephyr_sources()

Hogeボード + Spike SoCでcmake成功

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/
-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
-- Loading zephyr/boards/riscv/hoge/hoge.dts as base
hoge.dts.pre.tmp:22.17-25.5: Warning (simple_bus_reg): /soc/serial: missing or empty reg/ranges property
  also defined at hoge.dts.pre.tmp:37.8-39.3
Devicetree header saved to 'zephyr/build/zephyr/include/generated/devicetree_unfixed.h'
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/boards/riscv/hoge/hoge_defconfig'
Merged configuration 'zephyr/samples/hello_world/prj.conf'
Configuration saved to 'zephyr/build/zephyr/.config'
Kconfig header saved to 'zephyr/build/zephyr/include/generated/autoconf.h'

warning: UART_CONSOLE (defined at drivers/console/Kconfig:47) was assigned the value 'y' but got the
value 'n'. Check these unsatisfied dependencies: SERIAL_HAS_DRIVER (=n). See
http://docs.zephyrproject.org/latest/reference/kconfig/CONFIG_UART_CONSOLE.html and/or look up
UART_CONSOLE in the menuconfig/guiconfig interface. The Application Development Primer, Setting
Configuration Values, and Kconfig - Tips and Best Practices sections of the manual might be helpful
too.

-- The C compiler identification is GNU 8.3.0
-- The CXX compiler identification is GNU 8.3.0
-- The ASM compiler identification is GNU
-- Found assembler: /home/katsuhiro/x-tools/riscv64-zephyr-elf/bin/riscv64-zephyr-elf-gcc
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build

Kconfig.boardとhoge.dtsの変更点

diff --git a/boards/riscv/hoge/Kconfig.board b/boards/riscv/hoge/Kconfig.board
index 7ece0d6dee..c90614a391 100644
--- a/boards/riscv/hoge/Kconfig.board
+++ b/boards/riscv/hoge/Kconfig.board
@@ -2,4 +2,4 @@

 config BOARD_HOGE
        bool "Hoge target"
-       depends on SOC_RISCV_SIFIVE_FREEDOM
+       depends on SOC_RISCV_SPIKE


diff --git a/boards/riscv/hoge/hoge.dts b/boards/riscv/hoge/hoge.dts
index 21678f49ea..ee0c6589c4 100644
--- a/boards/riscv/hoge/hoge.dts
+++ b/boards/riscv/hoge/hoge.dts
@@ -2,7 +2,7 @@

 /dts-v1/;

-#include <riscv32-fe310.dtsi>
+#include <riscv32-spike.dtsi>

 / {
        model = "Hoge";

Kconfig.boardとhoge.dtsを変更してcmake

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
-- Loading zephyr/boards/riscv/hoge/hoge.dts as base
In file included from <command-line>:
zephyr/boards/riscv/hoge/hoge.dts:5:10: fatal error: riscv32-spike.dtsi: No such file or directory
 #include <riscv32-spike.dtsi>
          ^~~~~~~~~~~~~~~~~~~~
compilation terminated.
CMake Error at zephyr/cmake/dts.cmake:140 (message):
  command failed with return code: 1
Call Stack (most recent call first):
  zephyr/cmake/app/boilerplate.cmake:460 (include)
  CMakeLists.txt:5 (include)


-- Configuring incomplete, errors occurred!

riscv32-spike.dtsi

/* SPDX-License-Identifier: Apache-2.0 */

/ {
        #address-cells = <1>;
        #size-cells = <1>;
        compatible = "spike-dev";
        model = "spike";
        soc {
                #address-cells = <1>;
                #size-cells = <1>;
                compatible = "spike-soc", "simple-bus";
                ranges;

                clint: clint@2000000 {
                        compatible = "riscv,clint0";
                        reg = <0x02000000 0x10000>;
                        reg-names = "control";
                };

                mem: mem@80000000 {
                        compatible = "spike,mem";
                        reg = <0x80000000 0x4000>;
                        reg-names = "mem";
                };

                uart0: serial {
                        compatible = "spike,uart-spike";
                        label = "uart_0";
                };
        };
};

ボードのdefconfig: zephyr/boards/riscv/hoge/hoge_defconfig

# SPDX-License-Identifier: Apache-2.0

CONFIG_RISCV=y
CONFIG_SOC_SERIES_RISCV_SIFIVE_FREEDOM=y
CONFIG_SOC_RISCV_SIFIVE_FREEDOM=y
CONFIG_BOARD_HOGE=y
CONFIG_CONSOLE=y
CONFIG_PRINTK=y
CONFIG_SERIAL=y
CONFIG_UART_SIFIVE=y
CONFIG_UART_SIFIVE_PORT_0=y
CONFIG_UART_CONSOLE=y
CONFIG_PLIC=y
CONFIG_PINMUX=y
CONFIG_PINMUX_SIFIVE=y
CONFIG_RISCV_MACHINE_TIMER=y
CONFIG_GPIO=y
CONFIG_GPIO_SIFIVE=y
CONFIG_SYS_CLOCK_TICKS_PER_SEC=100
CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=10000000

ボードのdefconfigを追加した後のcmakeとビルド

$ cd build
$ rm -r *

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
-- Loading zephyr/boards/riscv/hoge/hoge.dts as base
Devicetree header saved to 'zephyr/build/zephyr/include/generated/devicetree_unfixed.h'
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/boards/riscv/hoge/hoge_defconfig'
Merged configuration 'zephyr/samples/hello_world/prj.conf'
Configuration saved to 'zephyr/build/zephyr/.config'
Kconfig header saved to 'zephyr/build/zephyr/include/generated/autoconf.h'
-- The C compiler identification is GNU 8.3.0
-- The CXX compiler identification is GNU 8.3.0
-- The ASM compiler identification is GNU
-- Found assembler: /home/katsuhiro/x-tools/riscv64-zephyr-elf/bin/riscv64-zephyr-elf-gcc
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build


$ ninja

[0/1] Re-running CMake...
-- Zephyr version: 2.1.99
-- Selected BOARD hoge
-- Loading zephyr/boards/riscv/hoge/hoge.dts as base
Devicetree header saved to 'zephyr/build/zephyr/include/generated/devicetree_unfixed.h'
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/build/zephyr/.config'
No change to configuration in 'zephyr/build/zephyr/.config'
No change to Kconfig header in 'zephyr/build/zephyr/include/generated/autoconf.h'
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build
[97/102] Linking C executable zephyr/zephyr_prebuilt.elf
Memory region         Used Size  Region Size  %age Used
             ROM:       12761 B        12 MB      0.10%
             RAM:        4048 B        16 KB     24.71%
        IDT_LIST:         553 B         2 KB     27.00%
[102/102] Linking C executable zephyr/zephyr.elf

DT_INST_ マクロを生成している箇所

# zephyr/cmake/dts.cmake

...

  #
  # Run gen_defines.py to create a .conf file and a header file
  #

  set(CMD_NEW_EXTRACT ${PYTHON_EXECUTABLE} ${ZEPHYR_BASE}/scripts/dts/gen_defines.py
  --dts ${BOARD}.dts.pre.tmp
  --bindings-dirs ${DTS_ROOT_BINDINGS}
  --conf-out ${DEVICETREE_CONF}
  --header-out ${DEVICETREE_UNFIXED_H}
  --dts-out ${PROJECT_BINARY_DIR}/zephyr.dts # As a debugging aid
  )

...


# zephyr/scripts/dts/gen_defines.py

def main():
    global conf_file
    global header_file
    global flash_area_num

    ...

    for node in sorted(edt.nodes, key=lambda node: node.dep_ordinal):
        write_node_comment(node)

        # Flash partition nodes are handled as a special case. It
        # would be nicer if we had bindings that would let us
        # avoid that, but this will do for now.
        if node.name.startswith("partition@"):
            write_flash_partition(node, flash_area_num)
            flash_area_num += 1

        if node.enabled and node.matching_compat:
            write_regs(node)
            write_irqs(node)
            write_props(node)
            write_clocks(node)
            write_spi_dev(node)
            write_bus(node)
            write_existence_flags(node)

    ...

def write_existence_flags(node):
    # Generate #defines of the form
    #
    #   #define DT_INST_<instance no.>_<compatible string> 1
    #
    # for enabled nodes. These are flags for which devices exist.

    for compat in node.compats:
        instance_no = node.edt.compat2enabled[compat].index(node)
        out(f"INST_{instance_no}_{str2ident(compat)}", 1)

...

def str2ident(s):
    # Converts 's' to a form suitable for (part of) an identifier

    return s.replace("-", "_") \
            .replace(",", "_") \
            .replace("@", "_") \
            .replace("/", "_") \
            .replace(".", "_") \
            .replace("+", "PLUS") \
            .upper()

menuconfigで手修正する箇所

$ ninja menuconfig

Architecture (x86 architecture)  --->
  ( ) RISCV architectureを選択

SoC/CPU/Configuration Selection (LiteX VexRiscv system implementation)  --->
  ( ) SiFive Freedom SOC implementationを選択

menuconfigで手修正後のビルド

$ ninja

zephyr/samples/hello_world/src/main.c:12:30: error: 'CONFIG_BOARD' undeclared (first use in this function); did you mean 'CONFIG_ARCH'?
  printk("Hello World! %s\n", CONFIG_BOARD);
                              ^~~~~~~~~~~~
                              CONFIG_ARCH

...

In file included from ../include/devicetree.h:12,
                 from ../soc/riscv/riscv-privilege/sifive-freedom/soc.h:15,
                 from ../include/arch/riscv/arch.h:25, 
                 from ../include/arch/cpu.h:23,
                 from ../include/kernel_includes.h:34, 
                 from ../include/kernel.h:17,
                 from zephyr/drivers/interrupt_controller/intc_plic.c:13:
zephyr/drivers/interrupt_controller/intc_plic.c: In function 'riscv_plic_irq_enable':
zephyr/include/generated/devicetree_fixups.h:8:25: error: 'DT_INST_0_SIFIVE_PLIC_1_0_0_IRQ_EN_BASE_ADDRESS' undeclared (first use in this function)
 #define DT_PLIC_IRQ_EN  DT_INST_0_SIFIVE_PLIC_1_0_0_IRQ_EN_BASE_ADDRESS
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...

Kconfig.defconfig

# SPDX-License-Identifier: Apache-2.0

if BOARD_HOGE

config BOARD
	default "hoge"

endif

hoge.dts

/* SPDX-License-Identifier: Apache-2.0 */

/dts-v1/;

#include <riscv32-fe310.dtsi>

/ {
	model = "Hoge Board";
	compatible = "hoge,hoge";

	chosen {
		zephyr,console = &uart0;
		zephyr,shell-uart = &uart0;
		zephyr,sram = &dtim;
		zephyr,flash = &flash0;
	};
};

&gpio0 {
	status = "okay";
};

&uart0 {
	status = "okay";
	current-speed = <115200>;
	clock-frequency = <16000000>;
};

&spi0 {
	status = "okay";

	#address-cells = <1>;
	#size-cells = <0>;
	reg = <0x10014000 0x1000 0x20400000 0xc00000>;
	flash0: flash@0 {
		compatible = "issi,is25lp128", "jedec,spi-nor";
		size = <134217728>;
		label = "FLASH0";
		jedec-id = [96 60 18];
		reg = <0>;
		// Dummy entry
		spi-max-frequency = <0>;
	};
};

デバイスツリー定義後のビルドエラー

$ ninja

...

riscv64-zephyr-elf/bin/ld: zephyr/arch/arch/riscv/core/libarch__riscv__core.a(isr.S.obj): in function `.L0 ':
zephyr/arch/riscv/core/isr.S:244: undefined reference to `_sw_isr_table'
riscv64-zephyr-elf/bin/ld: zephyr/kernel/libkernel.a(sched.c.obj): in function `z_reset_time_slice':
zephyr/kernel/sched.c:276: undefined reference to `z_clock_elapsed'
riscv64-zephyr-elf/bin/ld: zephyr/kernel/libkernel.a(timeout.c.obj): in function `elapsed':
zephyr/kernel/timeout.c:69: undefined reference to `z_clock_elapsed'
collect2: error: ld returned 1 exit status
%
ninja: build stopped: subcommand failed.

コンフィグ追加

General Architecture Options  --->
  Interrupt Configuration  --->
    [ ] Use generated IRQ tablesを選択

General Kernel Options  --->
  [ ] Execute in place

Device Drivers  --->
  [ ] Serial Drivers  ----
    [ ] Enable UART Interrupt supportを選択
    [ ] SiFive Freedom serial driver (NEW)  ----
      [ ] Enable SIFIVE Port 0 (NEW)  ---- を選択

  [ ] Console drivers  ---
    [ ] Use UART for console (NEW) を選択

  Timer Drivers  --->
    [ ] RISCV Machine Timerを選択

  [ ] GPIO Drivers  ----
    [ ] SiFive Freedom Processor GPIO driver (NEW)  ---- を選択

  [ ] Enable board pinmux driver  ----
    [ ] SiFive Freedom SOC pinmux driver (NEW)  ----

コンフィグ追加後、ビルド＆実行

$ ninja

...

Memory region         Used Size  Region Size  %age Used
             ROM:       13165 B        12 MB      0.10%
             RAM:        3808 B        16 KB     23.24%
        IDT_LIST:         569 B         2 KB     27.78%
[98/98] Linking C executable zephyr/zephyr.elf

$ /usr/bin/qemu-system-riscv32 -nographic -machine sifive_e -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel /home/katsuhiro/share/projects/oss/zephyr/build/zephyr/zephyr.elf

*** Booting Zephyr OS build zephyr-v2.1.0-1471-g7e7a4426d835  ***
Hello World! hoge

存在しないボードを指定したときの、ボード一覧

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
No board named 'hoge' found
see usage:

...

Supported Boards:

...

  riscv:
    hifive1
    hifive1_revb
    litex_vexriscv
    m2gl025_miv
    qemu_riscv32
    qemu_riscv64
    rv32m1_vega_ri5cy
    rv32m1_vega_zero_riscy
  x86:
    acrn
    gpmrb
    minnowboard
    qemu_x86_64
    qemu_x86_coverage
    qemu_x86
    qemu_x86_nommu
    up_squared

...

ボード一覧を調べている箇所

# zephyr/cmake/app/boilerplate.cmake

...

foreach(root ${BOARD_ROOT})
  # NB: find_path will return immediately if the output variable is
  # already set
  find_path(BOARD_DIR
    NAMES ${BOARD}_defconfig
    PATHS ${root}/boards/*/*
    NO_DEFAULT_PATH
    )
  if(BOARD_DIR AND NOT (${root} STREQUAL ${ZEPHYR_BASE}))
    set(USING_OUT_OF_TREE_BOARD 1)
  endif()

...

defconfigを足した後のボード一覧

$ mkdir boards/riscv/hoge
$ touch boards/riscv/hoge/hoge_defconfig

$ cmake -G Ninja -DBOARD=hoge2 ../samples/hello_world/

...

  riscv:
    hifive1
    hifive1_revb
    hoge        ★hogeが出てきた★
    litex_vexriscv
    m2gl025_miv
    qemu_riscv32
    qemu_riscv64
    rv32m1_vega_ri5cy
    rv32m1_vega_zero_riscy

...

defconfigを足した後のcmake

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Selected BOARD hoge
Parsing zephyr/Kconfig
zephyr/scripts/kconfig/kconfig.py: Kconfig.zephyr:26: 'zephyr/boards/riscv/hoge/Kconfig.defconfig' not found (in 'source "$(BOARD_DIR)/Kconfig.defconfig"'). Check that environment variables are set correctly (e.g. $srctree, which is set to 'zephyr'). Also note that unset environment variables expand to the empty string.
CMake Error at zephyr/cmake/kconfig.cmake:214 (message):
  command failed with return code: 1
Call Stack (most recent call first):
  zephyr/cmake/app/boilerplate.cmake:461 (include)
  CMakeLists.txt:5 (include)

-- Configuring incomplete, errors occurred!

Kconfig.defconfig, Kconfig.boardを足した後のcmake

$ touch boards/riscv/hoge/Kconfig.defconfig
$ touch boards/riscv/hoge/Kconfig.board

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/boards/riscv/hoge/hoge_defconfig'
Merged configuration 'zephyr/samples/hello_world/prj.conf'

warning: <choice> (defined at boards/Kconfig:19) defined with type unknown

error: Aborting due to non-whitelisted Kconfig warning 'warning: <choice> (defined at boards/Kconfig:19)
defined with type unknown'. If this warning doesn't point to an actual problem, you can add it to
the whitelist at the top of zephyr/scripts/kconfig/kconfig.py.

CMake Error at zephyr/cmake/kconfig.cmake:214 (message):
  command failed with return code: 1
Call Stack (most recent call first):
  zephyr/cmake/app/boilerplate.cmake:461 (include)
  CMakeLists.txt:5 (include)


-- Configuring incomplete, errors occurred!

エラーを出しているkconfig.cmake

# zephyr/cmake/kconfig.cmake

execute_process(
  COMMAND
  ${PYTHON_EXECUTABLE}
  ${ZEPHYR_BASE}/scripts/kconfig/kconfig.py
  ${input_configs_are_handwritten}
  ${KCONFIG_ROOT}
  ${DOTCONFIG}
  ${AUTOCONF_H}
  ${PARSED_KCONFIG_SOURCES_TXT}
  ${input_configs}
  WORKING_DIRECTORY ${APPLICATION_SOURCE_DIR}
  # The working directory is set to the app dir such that the user
  # can use relative paths in CONF_FILE, e.g. CONF_FILE=nrf5.conf
  RESULT_VARIABLE ret
  )
if(NOT "${ret}" STREQUAL "0")
  message(FATAL_ERROR "command failed with return code: ${ret}")
endif()

choiceのエラーの原因

# boards/Kconfig

...

# Note: $BOARD_DIR might be a glob pattern

choice
	prompt "Board Selection"

source "$(BOARD_DIR)/Kconfig.board"    ★このファイルが空★

endchoice

Kconfig.boardを書き換え

# SPDX-License-Identifier: Apache-2.0
 
config BOARD_HOGE
	bool "Hoge target"
	depends on SOC_RISCV_SIFIVE_FREEDOM

Kconfig.boardを書き換えた後にcmake実行

$ cmake -G Ninja -DBOARD=hoge ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD hoge
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/boards/riscv/hoge/hoge_defconfig'
Merged configuration 'zephyr/samples/hello_world/prj.conf'
Configuration saved to 'zephyr/build/zephyr/.config'
-- The C compiler identification is GNU 8.3.0
-- The CXX compiler identification is GNU 8.3.0
-- The ASM compiler identification is GNU
-- Found assembler: /home/katsuhiro/x-tools/riscv64-zephyr-elf/bin/riscv64-zephyr-elf-gcc
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build


$ ninja

[0/1] Re-running CMake...
-- Zephyr version: 2.1.99
-- Selected BOARD hoge
Parsing zephyr/Kconfig
Loaded configuration 'zephyr/build/zephyr/.config'
No change to 'zephyr/build/zephyr/.config'
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: zephyr/build
[5/83] Building C object zephyr/CMakeFiles/offsets.dir/arch/riscv/core/offsets/offsets.c.obj
FAILED: zephyr/CMakeFiles/offsets.dir/arch/riscv/core/offsets/offsets.c.obj
ccache /home/katsuhiro/x-tools/riscv64-zephyr-elf/bin/riscv64-zephyr-elf-gcc -DBUILD_VERSION=zephyr-v2.1.0-1471-g7e7a4426d835 -DKERNEL -D_FORTIFY_SOURCE=2 -D__ZEPHYR__=1 -I../kernel/include -I../arch/riscv/include -I../include -Izephyr/include/generated -I../soc/riscv/litex-vexriscv -isystem ../lib/libc/minimal/include -isystem /home/katsuhiro/x-tools/riscv64-zephyr-elf/lib/gcc/riscv64-zephyr-elf/8.3.0/include -isystem /home/katsuhiro/x-tools/riscv64-zephyr-elf/lib/gcc/riscv64-zephyr-elf/8.3.0/include-fixed -Os -imacroszephyr/build/zephyr/include/generated/autoconf.h -ffreestanding -fno-common -g -mabi=ilp32 -march=rv32ima -imacroszephyr/include/toolchain/zephyr_stdint.h -Wall -Wformat -Wformat-security -Wno-format-zero-length -Wno-main -Wno-pointer-sign -Wpointer-arith -Wno-unused-but-set-variable -Werror=implicit-int -fno-asynchronous-unwind-tables -fno-pie -fno-pic -fno-strict-overflow -fno-reorder-functions -fno-defer-pop -fmacro-prefix-map=zephyr/samples/hello_world=CMAKE_SOURCE_DIR -fmacro-prefix-map=zephyr=ZEPHYR_BASE -ffunction-sections -fdata-sections -std=c99 -nostdinc -MD -MT zephyr/CMakeFiles/offsets.dir/arch/riscv/core/offsets/offsets.c.obj -MF zephyr/CMakeFiles/offsets.dir/arch/riscv/core/offsets/offsets.c.obj.d -o zephyr/CMakeFiles/offsets.dir/arch/riscv/core/offsets/offsets.c.obj   -c zephyr/arch/riscv/core/offsets/offsets.c
In file included from ../include/sys/atomic.h:468,
                 from ../include/kernel_includes.h:21, 
                 from ../include/kernel.h:17,
                 from zephyr/arch/riscv/core/offsets/offsets.c:16:
zephyr/include/generated/syscalls/atomic.h:25:19: error: conflicting types for 'atomic_cas'
 static inline int atomic_cas(atomic_t * target, atomic_val_t old_value, atomic_val_t new_value)
                   ^~~~~~~~~~
In file included from ../include/kernel_includes.h:21, 
                 from ../include/kernel.h:17,
                 from zephyr/arch/riscv/core/offsets/offsets.c:16:
../include/sys/atomic.h:44:20: note: previous definition of 'atomic_cas' was here
 static inline bool atomic_cas(atomic_t *target, atomic_val_t old_value,

QEMUの起動コマンド

$ /usr/bin/qemu-system-riscv32 -nographic -machine sifive_e -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel zephyr/build/zephyr/zephyr.elf -s -S

0x1000にあるコード

   0x1000:      lui     t0,0x20400
=> 0x1004:      jr      t0
   0x1008:      unimp
   0x100a:      unimp

0x1000にあるコード

$ riscv64-zephyr-elf-readelf -a build/zephyr/zephyr.elf  | less

...

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] vector            PROGBITS        20400000 000094 000010 00  AX  0   0  4
  [ 2] exceptions        PROGBITS        20400010 0000a4 000258 00  AX  0   0  4
  [ 3] text              PROGBITS        20400268 0002fc 002ad4 00  AX  0   0  4
  [ 4] sw_isr_table      PROGBITS        20402d3c 002dd0 000200 00  WA  0   0  4
  [ 5] devconfig         PROGBITS        20402f3c 002fd0 000060 00   A  0   0  4
  [ 6] rodata            PROGBITS        20402f9c 003030 000215 00   A  0   0  4
  [ 7] datas             PROGBITS        80000000 003248 000018 00  WA  0   0  4
  [ 8] initlevel         PROGBITS        80000018 003260 000060 00  WA  0   0  4
  [ 9] _k_mutex_area     PROGBITS        80000078 0032c0 000014 00  WA  0   0  4
  [10] bss               NOBITS          80000090 0032e0 00013c 00  WA  0   0  8
  [11] noinit            NOBITS          800001d0 0032e0 000e00 00  WA  0   0 16

...

0x20400000にあるコード

zephyr/zephyr.elf:     file format elf32-littleriscv


Disassembly of section vector:

20400000 <__start>:

        /*
         * Set mtvec (Machine Trap-Vector Base-Address Register)
         * to __irq_wrapper.
         */
        la t0, __irq_wrapper
20400000:       00000297                auipc   t0,0x0
20400004:       01028293                addi    t0,t0,16 # 20400010 <__irq_wrapper>
        csrw mtvec, t0
20400008:       30529073                csrw    mtvec,t0

        /* Jump to __initialize */
        tail __initialize
2040000c:       4b40106f                j       204014c0 <__initialize>

ボード用のデバイスツリーのchosenノード

        chosen {
                zephyr,console = &uart0;
                zephyr,shell-uart = &uart0;
                zephyr,sram = &dtim;
                zephyr,flash = &flash0;
        };

Flashのサイズを見ている箇所

# zephyr/scripts/dts/gen_defines.py

...

def write_flash_node(edt):
    # Writes output for the top-level flash node pointed at by
    # zephyr,flash in /chosen

    node = edt.chosen_node("zephyr,flash")

    out_comment(f"/chosen/zephyr,flash ({node.path if node else 'missing'})")

    if not node:
        # No flash node. Write dummy values.
        out("FLASH_BASE_ADDRESS", 0)
        out("FLASH_SIZE", 0)
        return

    if len(node.regs) != 1:
        err("expected zephyr,flash to have a single register, has "
            f"{len(node.regs)}")

    if node.on_bus == "spi" and len(node.bus_node.regs) == 2:
        reg = node.bus_node.regs[1]  # QSPI flash
    else:
        reg = node.regs[0]

    out("FLASH_BASE_ADDRESS", hex(reg.addr))
    if reg.size:
        out("FLASH_SIZE", reg.size//1024)

...

エントリーポイントを決めている箇所

// zephyr/include/arch/riscv/common/linker.ld

MEMORY
{
#ifdef CONFIG_XIP
    ROM (rx)  : ORIGIN = DT_FLASH_BASE_ADDRESS, LENGTH = KB(DT_FLASH_SIZE)
#endif
    RAM (rwx) : ORIGIN = CONFIG_SRAM_BASE_ADDRESS, LENGTH = KB(CONFIG_SRAM_SIZE)
    /* Used by and documented in include/linker/intlist.ld */
    IDT_LIST  (wx)      : ORIGIN = 0xFFFFF7FF, LENGTH = 2K
}

crosstool-NG RISC-V版のビルド

$ ./ct-ng menuconfig

Target options  --->
  Target Architecture (riscv)  --->
  [*] Build a multilib toolchain (READ HELP!!!)
  Bitness: (64-bit)  --->
  (rv32ima) Architecture level
  (ilp32) Generate code for the specific ABI

Toolchain options  --->
  (zephyr) Tuple's vendor string

Debug facilities  --->
  [*] gdb  --->
    [*]     Build a static cross gdb

ZephyrのCMakeスクリプト

zephyr/cmake/toolchain/xtools/target.cmake

set(CROSS_COMPILE_TARGET_riscv   riscv64-zephyr-elf)

set(CROSS_COMPILE_TARGET ${CROSS_COMPILE_TARGET_${ARCH}})

-    list(APPEND TOOLCHAIN_C_FLAGS -mabi=ilp32 -march=rv32ima)
+    list(APPEND TOOLCHAIN_C_FLAGS -mabi=ilp32f -march=rv32gc)

環境変数のセットアップとcmakeの実行

$ cat ~/.zephyrrc 

export ZEPHYR_TOOLCHAIN_VARIANT=xtools
export XTOOLS_TOOLCHAIN_PATH=/home/katsuhiro/x-tools

$ cd zephyr
$ source zephyr-env.sh

$ mkdir build
$ cd build

$ cmake -G Ninja -DBOARD=qemu_riscv32 ../samples/hello_world/

-- Zephyr version: 2.1.99
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.7.6", minimum required is "3.6")
-- Selected BOARD qemu_riscv32
-- Loading /home/katsuhiro/share/projects/oss/zephyr/boards/riscv/qemu_riscv32/qemu_riscv32.dts as base
Devicetree configuration written to /home/katsuhiro/share/projects/oss/zephyr/build/zephyr/include/generated/devicetree.conf
Parsing /home/katsuhiro/share/projects/oss/zephyr/Kconfig
Loaded configuration '/home/katsuhiro/share/projects/oss/zephyr/boards/riscv/qemu_riscv32/qemu_riscv32_defconfig'
Merged configuration '/home/katsuhiro/share/projects/oss/zephyr/samples/hello_world/prj.conf'
Configuration saved to '/home/katsuhiro/share/projects/oss/zephyr/build/zephyr/.config'
-- The C compiler identification is GNU 8.3.0
-- The CXX compiler identification is GNU 8.3.0
-- The ASM compiler identification is GNU
-- Found assembler: /home/katsuhiro/x-tools/riscv64-zephyr-elf/bin/riscv64-zephyr-elf-gcc
-- Cache files will be written to: /home/katsuhiro/.cache/zephyr
-- Configuring done
-- Generating done
-- Build files have been written to: /home/katsuhiro/share/projects/oss/zephyr/build

Zephyr OS実行

$ /usr/bin/qemu-system-riscv32 -nographic -machine sifive_e -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel /home/katsuhiro/share/projects/oss/zephyr/build/zephyr/zephyr.elf -s -S

(gdbからcontinueをすると、下記が出力される)

*** Booting Zephyr OS build zephyr-v2.1.0-1471-g7e7a4426d835  ***
Hello World! qemu_riscv32

GDB接続

$ riscv64-zephyr-elf-gdb

GNU gdb (crosstool-NG 1.24.0.60-a152d61) 8.3.1
Copyright (C) 2019 Free Software Foundation, Inc.

...

(gdb) set arch riscv:rv32
The target architecture is assumed to be riscv:rv32

(gdb) target remote localhost:1234

Remote debugging using localhost:1234
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.
0x00001000 in ?? ()

(gdb) continue

Continuing.

GCC HEAD (GCC 10.0相当) でglibc 2.28をビルドするとコンパイルエラー

./../include/libc-symbols.h:534:26: error: '__EI___errno_location' specifies less restrictive attributes than its target '__errno_location': 'const', 'nothrow' [-Werror=missing-attributes]
  534 |   extern __typeof (name) __EI_##name \
      |                          ^~~~~

GCC 8.3でglibc 2.30をビルドするとリンクエラー

crosstool-builder-new-aarch64/buildroot/lib/gcc/aarch64-unknown-linux-gnu/8.3.0/../../../../aarch64-unknown-linux-gnu/bin/ld: crosstool-builder-new-aarch64/build/glibc/support/links-dso-program.o: Relocations in generic ELF (EM: 62)
crosstool-builder-new-aarch64/buildroot/lib/gcc/aarch64-unknown-linux-gnu/8.3.0/../../../../aarch64-unknown-linux-gnu/bin/ld: crosstool-builder-new-aarch64/build/glibc/support/links-dso-program.o: Relocations in generic ELF (EM: 62)
...

glibc/support下に生成されたオブジェクト

build/glibc/support$ file *.o

echo-container.o:    ELF 64-bit LSB relocatable, ARM aarch64, version 1 (SYSV), with debug_info, not stripped
links-dso-program.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), with debug_info, not stripped    ★★★★これ★★★★
shell-container.o:   ELF 64-bit LSB relocatable, ARM aarch64, version 1 (SYSV), with debug_info, not stripped
stamp.o:             empty
test-container.o:    ELF 64-bit LSB relocatable, ARM aarch64, version 1 (SYSV), with debug_info, not stripped
true-container.o:    ELF 64-bit LSB relocatable, ARM aarch64, version 1 (SYSV), with debug_info, not stripped

glibcのビルドエラーをあえて無視するパッチ

diff --git a/Makeconfig b/Makeconfig
index fd36c58c04..106688e210 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -916,7 +916,8 @@ ifeq	"$(strip $(+cflags))" ""
 endif	# $(+cflags) == ""
 
 +cflags += $(cflags-cpu) $(+gccwarn) $(+merge-constants) $(+math-flags) \
-	   $(+stack-protector)
+	   $(+stack-protector) \
+	   -Wno-zero-length-bounds -Wno-array-bounds -Wno-maybe-uninitialized
 +gcc-nowarn := -w
 
 # Each sysdeps directory can contain header files that both will be

glibcのsupport/links-dso-programをビルドさせないパッチ

diff --git a/support/Makefile b/support/Makefile
index ab66913a02..19c3de2043 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -184,12 +184,12 @@ CFLAGS-support_paths.c = \
 		-DSBINDIR_PATH=\"$(sbindir)\" \
 		-DROOTSBINDIR_PATH=\"$(rootsbindir)\"
 
-ifeq (,$(CXX))
-LINKS_DSO_PROGRAM = links-dso-program-c
-else
-LINKS_DSO_PROGRAM = links-dso-program
-LDLIBS-links-dso-program = -lstdc++ -lgcc -lgcc_s $(libunwind)
-endif
+#ifeq (,$(CXX))
+#LINKS_DSO_PROGRAM = links-dso-program-c
+#else
+#LINKS_DSO_PROGRAM = links-dso-program
+#LDLIBS-links-dso-program = -lstdc++ -lgcc -lgcc_s $(libunwind)
+#endif
 
 ifeq (yes,$(have-selinux))
 LDLIBS-$(LINKS_DSO_PROGRAM) += -lselinux