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configs/qemu_sh4*: switch back to disk emulation

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Back in commit
44a6b7866c ("configs/qemu_sh4*: switch
to initramfs"), the Qemu SuperH defconfigs were switched to initramfs
due to a bug in the Qemu disk emulation.

However, the initramfs solution has an issue: if the initramfs is
slightly too large (like just 6 MB!), the system no longer boots.

Since the disk emulation problem has apparently been resolved in Qemu
10 (according to testing), let's switch back to this.

In addition to essentially reverting
44a6b7866c, we also need to adjust the
kernel configuration so that the kernel takes its command line for the
bootloader (in our case from the Qemu -append option). Otherwise an
hardcoded command line is used, which doesn't mount /dev/sda as the
root filesystem.

This update has been tested on Gitlab CI:

  https://gitlab.com/tpetazzoni/buildroot/-/pipelines/1968267919

Thanks to Romain Naour for pointing to the initramfs size as being the
issue.

Cc: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
This commit is contained in:
Thomas Petazzoni
2025-08-05 21:07:26 +02:00
committed by Julien Olivain
parent 0e450a0b08
commit 5edce69188
6 changed files with 6 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
board/qemu/sh4-r2d/linux.config
View File

@@ -5,6 +5,7 @@ CONFIG_MEMORY_START=0x0c000000
CONFIG_FLATMEM_MANUAL=y
CONFIG_SH_RTS7751R2D=y
CONFIG_RTS7751R2D_PLUS=y
CONFIG_CMDLINE_FROM_BOOTLOADER=y
CONFIG_HEARTBEAT=y
CONFIG_PCI=y
CONFIG_NET=y

2
board/qemu/sh4-r2d/readme.txt
View File

@@ -1,6 +1,6 @@
Run the emulation with:
qemu-system-sh4 -M r2d -kernel output/images/zImage -append "console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user # qemu_sh4_r2d_defconfig
qemu-system-sh4 -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "rootwait root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user # qemu_sh4_r2d_defconfig
The login prompt will appear in the terminal that started Qemu.
The graphical window is the framebuffer.

1
board/qemu/sh4eb-r2d/linux.config
View File

@@ -6,6 +6,7 @@ CONFIG_FLATMEM_MANUAL=y
CONFIG_CPU_BIG_ENDIAN=y
CONFIG_SH_RTS7751R2D=y
CONFIG_RTS7751R2D_PLUS=y
CONFIG_CMDLINE_FROM_BOOTLOADER=y
CONFIG_HEARTBEAT=y
CONFIG_PCI=y
CONFIG_NET=y

2
board/qemu/sh4eb-r2d/readme.txt
View File

@@ -1,6 +1,6 @@
Run the emulation with:
qemu-system-sh4eb -M r2d -kernel output/images/zImage -append "console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user # qemu_sh4eb_r2d_defconfig
qemu-system-sh4eb -M r2d -kernel output/images/zImage -drive file=output/images/rootfs.ext2,if=ide,format=raw -append "rootwait root=/dev/sda console=ttySC1,115200 noiotrap" -serial null -serial stdio -net nic,model=rtl8139 -net user # qemu_sh4eb_r2d_defconfig
The login prompt will appear in the terminal that started Qemu.
The graphical window is the framebuffer.

2
configs/qemu_sh4_r2d_defconfig
View File

@@ -12,7 +12,7 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.12.27"
BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/sh4-r2d/linux.config"
BR2_LINUX_KERNEL_ZIMAGE=y
BR2_TARGET_ROOTFS_INITRAMFS=y
BR2_TARGET_ROOTFS_EXT2=y
# BR2_TARGET_ROOTFS_TAR is not set
BR2_PACKAGE_HOST_QEMU=y
BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE=y

2
configs/qemu_sh4eb_r2d_defconfig
View File

@@ -12,7 +12,7 @@ BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.12.27"
BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/sh4eb-r2d/linux.config"
BR2_LINUX_KERNEL_ZIMAGE=y
BR2_TARGET_ROOTFS_INITRAMFS=y
BR2_TARGET_ROOTFS_EXT2=y
# BR2_TARGET_ROOTFS_TAR is not set
BR2_PACKAGE_HOST_QEMU=y
BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE=y