[solved] risc-v qemu kernel not starting

[nukulartechniker]

solved by compiling Virtio block driver (CONFIG_SCSI_VIRTIO) inside kernel, not as module.
https://wiki.gentoo.org/wiki/QEMU/Linux_guest#Kernel



Installing gentoo on a qemu risc-v machine, kernel will not load

just for fun I started to install gentoo on a qemu risc-v machine. so far everything is working really well. basically I used an ubuntu 22.04 Image to startup the machine and then did a stage 3 install following partly the amd64 handbook.

the only package giving me headaches was grub, but with a little tinkering it finally build (and works )

right now I have a problem to boot using a gentoo kernel.
the vm starts up quite fine using the ubuntu kernel that came with the preinstalled image, i just copied kernel, initramfs and modules to get things startet.

the boot process seems to be the following open spi -> uboot -> grub -> linux kernel. this works fine for the ubuntu kernel. Am I missing something obvious?

I am using qemu 7, the command to start the vm is the following:

Code: Select all

qemu-system-riscv64 \
-machine virt \
-m 16G \
-smp 8 \
-kernel ./u-boot-qemu/uboot.elf \
-nographic \
-object rng-random,filename=/dev/urandom,id=rng \
-device virtio-rng-device,rng=rng \
-device virtio-net-device,netdev=eth0 \
-netdev bridge,br=virbr0,id=eth0 \
-drive file=gentoo.qcow2,if=virtio,id=gentoo,index=0

then openspi loads, uboot loads and finally grub

Code: Select all

OpenSBI v1.0

... ascii art removed

Platform Name             : riscv-virtio,qemu
Platform Features         : medeleg
Platform HART Count       : 8
Platform IPI Device       : aclint-mswi
Platform Timer Device     : aclint-mtimer @ 10000000Hz
Platform Console Device   : uart8250
Platform HSM Device       : ---
Platform Reboot Device    : sifive_test
Platform Shutdown Device  : sifive_test
Firmware Base             : 0x80000000
Firmware Size             : 308 KB
Runtime SBI Version       : 0.3

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*,1*,2*,3*,4*,5*,6*,7*
Domain0 Region00          : 0x0000000002000000-0x000000000200ffff (I)
Domain0 Region01          : 0x0000000080000000-0x000000008007ffff ()
Domain0 Region02          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address      : 0x0000000080200000
Domain0 Next Arg1         : 0x00000000bf000000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART ISA             : rv64imafdcsuh
Boot HART Features        : scounteren,mcounteren,time
Boot HART PMP Count       : 16
Boot HART PMP Granularity : 4
Boot HART PMP Address Bits: 54
Boot HART MHPM Count      : 0
Boot HART MIDELEG         : 0x0000000000001666
Boot HART MEDELEG         : 0x0000000000f0b509


U-Boot 2022.07-rc4+dfsg-1 (Jun 08 2022 - 19:06:20 +0000)

CPU:   rv64imafdcsuh
Model: riscv-virtio,qemu
DRAM:  16 GiB
Core:  33 devices, 14 uclasses, devicetree: board
Flash: 32 MiB
Loading Environment from nowhere... OK
In:    uart@10000000
Out:   uart@10000000
Err:   uart@10000000
Net:   eth0: virtio-net#1
Hit any key to stop autoboot:  0 

Device 0: 1af4 VirtIO Block Device
            Type: Hard Disk
            Capacity: 131072.0 MB = 128.0 GB (268435456 x 512)
... is now current device
Scanning virtio 0:1...
** Unable to read file / **
Failed to load '/'
** Unable to read file ubootefi.var **
Failed to load EFI variables
BootOrder not defined
EFI boot manager: Cannot load any image
Found EFI removable media binary efi/boot/bootriscv64.efi
151552 bytes read in 1 ms (144.5 MiB/s)
Booting /efi\boot\bootriscv64.efi
Welcome to GRUB!

my gentoo kernel config
https://github.com/ccharon/docs/blob/ma ... too/config

Boot Message when everything works (ubuntu kernel)

Linux 5.15.0-1014-generic wird geladen …
Initiale Ramdisk wird geladen …
EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Exiting boot services...
[ 0.000000] Linux version 5.15.0-1014-generic (buildd@riscv64-qemu-lgw01-088) (gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0, GNU ld (GNU Binutils for Ubuntu) 2.38) #16-Ubuntu SMP Thu Jun 2 13:45:22 UTC 2022 (Ubuntu 5.15.0-1014.16-generic 5.15.35)

Boot Message with gentoo kernel (note: i omitted an initramfs on purpose, gpt, ext4 and so on are compiled in so this should not be needed)

Linux 5.18.12-gentoo wird geladen …
EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Exiting boot services...

when trying to load the gentoo kernel the part with "EFI stub: Using DTB from configuration table" is faster ... maybe the gentoo kernel does not recognize the devicetree and therefor can not boot?

[quilosaq]

Try compiling Virtio block driver (CONFIG_SCSI_VIRTIO) inside kernel, not as module.

https://wiki.gentoo.org/wiki/QEMU/Linux_guest#Kernel

[nukulartechniker]

that did the trick, now the kernel is booting with 2 things to investigate..

1. it only works when i use an initramfs. i have to look which additional drivers need to be compiled in.
2. the kernel does not write message to the serial console.