[Buildroot] [PATCH 1/1] configs/spike_riscv32: new defconfig

* [Buildroot] [PATCH 1/1] configs/spike_riscv32: new defconfig
@ 2024-06-22 11:46 Julien Olivain
  2024-07-12 13:59 ` Thomas Petazzoni via buildroot
  0 siblings, 1 reply; 2+ messages in thread
From: Julien Olivain @ 2024-06-22 11:46 UTC (permalink / raw)
  To: buildroot; +Cc: Julien Olivain

Buildroot commit [1] updated riscv-isa-sim (Spike), which now includes
a NS16550 uart emulation. This can be used by RV32 Linux Kernel. This
commit introduce a defconfig for running Linux on Spike RISC-V 32-bit
ISA simulator.

[1] https://gitlab.com/buildroot.org/buildroot/-/commit/853b7661bf5ddca5d4b81964ef1a19a133beac85

Signed-off-by: Julien Olivain <ju.o@free.fr>
---
Patch tested on branch master at commit 853b766 with commands:

    utils/docker-run make check-package
    ...
    OK

    make spike_riscv32_defconfig
    make
    board/spike/riscv32/start.sh
    ...
    Welcome to Buildroot
    buildroot login:
---
 DEVELOPERS                                    |  1 +
 .../patches/linux-headers/linux-headers.hash  |  1 +
 board/spike/riscv32/patches/linux/linux.hash  |  2 ++
 .../riscv32/patches/opensbi/opensbi.hash      |  2 ++
 board/spike/riscv32/readme.txt                | 30 +++++++++++++++++++
 board/spike/riscv32/start.sh                  | 23 ++++++++++++++
 configs/spike_riscv32_defconfig               | 17 +++++++++++
 7 files changed, 76 insertions(+)
 create mode 120000 board/spike/riscv32/patches/linux-headers/linux-headers.hash
 create mode 100644 board/spike/riscv32/patches/linux/linux.hash
 create mode 100644 board/spike/riscv32/patches/opensbi/opensbi.hash
 create mode 100644 board/spike/riscv32/readme.txt
 create mode 100755 board/spike/riscv32/start.sh
 create mode 100644 configs/spike_riscv32_defconfig

diff --git a/DEVELOPERS b/DEVELOPERS
index 8a5cceba78e..f8bcfc57c1b 100644
--- a/DEVELOPERS
+++ b/DEVELOPERS
@@ -1750,6 +1750,7 @@ F:	board/technexion/imx8mpico/
 F:	configs/imx8mmpico_defconfig
 F:	configs/imx8mpico_defconfig
 F:	configs/qemu_riscv64_virt_efi_defconfig
+F:	configs/spike_riscv32_defconfig
 F:	configs/spike_riscv64_defconfig
 F:	package/fluid-soundfont/
 F:	package/fluidsynth/
diff --git a/board/spike/riscv32/patches/linux-headers/linux-headers.hash b/board/spike/riscv32/patches/linux-headers/linux-headers.hash
new file mode 120000
index 00000000000..5808d92afe8
--- /dev/null
+++ b/board/spike/riscv32/patches/linux-headers/linux-headers.hash
@@ -0,0 +1 @@
+../linux/linux.hash
\ No newline at end of file
diff --git a/board/spike/riscv32/patches/linux/linux.hash b/board/spike/riscv32/patches/linux/linux.hash
new file mode 100644
index 00000000000..a3b67a09a47
--- /dev/null
+++ b/board/spike/riscv32/patches/linux/linux.hash
@@ -0,0 +1,2 @@
+# From https://cdn.kernel.org/pub/linux/kernel/v6.x/sha256sums.asc
+sha256  fce3ee728712ed063aa8c14a8756c8ff8c7a46ba3827f61d2b04a73c7cf5dd9e  linux-6.6.35.tar.xz
diff --git a/board/spike/riscv32/patches/opensbi/opensbi.hash b/board/spike/riscv32/patches/opensbi/opensbi.hash
new file mode 100644
index 00000000000..bc4058abe62
--- /dev/null
+++ b/board/spike/riscv32/patches/opensbi/opensbi.hash
@@ -0,0 +1,2 @@
+# Locally calculated
+sha256  319b62a4186fbce9b81a0c5f0ec9f003a10c808397a72138bc9745d9b87b1eb1  opensbi-1.4.tar.gz
diff --git a/board/spike/riscv32/readme.txt b/board/spike/riscv32/readme.txt
new file mode 100644
index 00000000000..9cc49af9df3
--- /dev/null
+++ b/board/spike/riscv32/readme.txt
@@ -0,0 +1,30 @@
+Linux on Spike RISC-V 32-bit ISA simulator
+==========================================
+
+This configuration provides a minimal working setup to run a Linux
+kernel in the Spike RISC-V ISA simulator.
+
+The Spike ISA simulator can be an interresting alternative to Qemu, in
+some specific cases. For example: simulating new instructions (see [1]),
+simulating riscv-openocd/gdb debug sessions (see [2], [3]), or
+generating an accurate per-instruction log of execution (see
+riscv-isa-sim spike -l option)...
+
+To run Buildroot Linux in Spike, use the commands:
+
+    make spike_riscv32_defconfig
+    make
+    ./board/spike/riscv32/start.sh
+
+The boot is made with the standard RISC-V OpenSBI boot loader. In
+order to keep the simulation simple, the rootfs is passed as an initrd
+ramfs.
+
+[1].
+https://github.com/riscv-software-src/riscv-isa-sim/tree/v1.1.0#simulating-a-new-instruction
+
+[2].
+https://github.com/riscv-software-src/riscv-isa-sim/tree/v1.1.0#debugging-with-gdb
+
+[3].
+https://github.com/riscv-collab/riscv-openocd
diff --git a/board/spike/riscv32/start.sh b/board/spike/riscv32/start.sh
new file mode 100755
index 00000000000..43d2d9dcde1
--- /dev/null
+++ b/board/spike/riscv32/start.sh
@@ -0,0 +1,23 @@
+#! /bin/sh
+
+SCRIPT_DIR="$(dirname "$0")"
+BR_BASEDIR="$(readlink -e "${SCRIPT_DIR}/../../..")"
+
+# spike uses dtc at runtime startup, so make sure buildroot host
+# directory is in the PATH
+export PATH="${BR_BASEDIR}/output/host/usr/bin:$PATH"
+
+# Use Buildroot host spike by default, but allow the caller to
+# redefine another spike binary
+: "${SPIKE:=spike}"
+
+# Note 1: Kernel with initrd fail to boot on riscv32 when the system
+# has more than 1GB of RAM. So we set exactly this amount of RAM.
+# Note 2: The default spike ISA is RV64IMAFDC_zicntr_zihpm, so we need
+# to force the RV32 ISA here.
+exec "${SPIKE}" \
+    -m1024 \
+    --initrd "${BR_BASEDIR}"/output/images/rootfs.cpio \
+    --isa="RV32IMAFDC_zicntr_zihpm" \
+    "${@}" \
+    "${BR_BASEDIR}"/output/images/fw_payload.elf
diff --git a/configs/spike_riscv32_defconfig b/configs/spike_riscv32_defconfig
new file mode 100644
index 00000000000..6ea12dc1fb7
--- /dev/null
+++ b/configs/spike_riscv32_defconfig
@@ -0,0 +1,17 @@
+BR2_riscv=y
+BR2_RISCV_32=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_6=y
+BR2_GLOBAL_PATCH_DIR="board/spike/riscv32/patches"
+BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
+BR2_LINUX_KERNEL=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.6.35"
+BR2_LINUX_KERNEL_DEFCONFIG="rv32"
+BR2_TARGET_ROOTFS_CPIO=y
+# BR2_TARGET_ROOTFS_TAR is not set
+BR2_TARGET_OPENSBI=y
+BR2_TARGET_OPENSBI_CUSTOM_VERSION=y
+BR2_TARGET_OPENSBI_CUSTOM_VERSION_VALUE="1.4"
+BR2_TARGET_OPENSBI_PLAT="generic"
+BR2_TARGET_OPENSBI_LINUX_PAYLOAD=y
+BR2_PACKAGE_HOST_RISCV_ISA_SIM=y
-- 
2.45.2

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