Booting Linux from U-Boot in qemu-system-riscv64?

Booting Linux from U-Boot in qemu-system-riscv64?

[Michael Opdenacker]

Greetings,

To prepare an embedded Linux demo (on RiscV), I'm trying to boot Linux
from U-Boot in qemu-system-riscv64, using the "virt" emulated machine...
Note that I'm using QEMU 5.0.

The well documented way to boot Linux works:

In Linux master:
CROSS_COMPILE=riscv64-linux-gnu- (toolchain built by Buildroot)
ARCH=riscv
make defconfig
make

In opensbi:
make PLATFORM=generic FW_PAYLOAD_PATH=../linux/arch/riscv/boot/Image

Running QEMU:
qemu-system-riscv64 -nographic? -machine virt -kernel
opensbi/build/platform/generic/firmware/fw_payload.elf -append
"console=ttyS0"

I can also boot U-Boot, but cannot manage to boot the Linux kernel with it:

In U-Boot mainline:

CROSS_COMPILE=riscv64-linux-gnu-
make qemu-riscv64_smode_defconfig
Modify the environment:
- Unset CONFIG_ENV_IS_NOWHERE
- CONFIG_ENV_IS_IN_FAT=y
- CONFIG_ENV_FAT_INTERFACE="virtio"
- CONFIG_ENV_FAT_DEVICE_AND_PART="0:1"
- CONFIG_ENV_FAT_FILE="uboot.env"
make

Note that having U-Boot in "S" mode seems to be required to boot Linux.
If U-Boot is in "M" mode, it works, but there are faults (as expected)
when trying to execute Linux.

In opensbi:
make PLATFORM=generic FW_PAYLOAD_PATH=../u-boot/u-boot.bin

I then prepared a disk.img image with a first FAT partition containing:
- A "dtb" file captured from the first Linux boot (from /sys/firmware/fdt)
- A "uImage" file made from the command:
mkimage -A riscv -O linux -C none? -T kernel -a 80200000 -e 80200000 -n
"Linux" -d arch/riscv/boot/Image uImage

Then I'm starting QEMU as follows:

qemu-system-riscv64 -m 1G -nographic? -machine virt -bios
opensbi/build/platform/generic/firmware/fw_payload.bin -device
virtio-blk-device,drive=hd0 -drive file=disk.img,format=raw,id=hd0

OpenSBI v0.8-58-g781cafd
?? ____??????????????????? _____ ____ _____
? / __ \????????????????? / ____|? _ \_?? _|
?| |? | |_ __?? ___ _ __ | (___ | |_) || |
?| |? | | '_ \ / _ \ '_ \ \___ \|? _ < | |
?| |__| | |_) |? __/ | | |____) | |_) || |_
? \____/| .__/ \___|_| |_|_____/|____/_____|
??????? | |
??????? |_|

Platform Name???????????? : riscv-virtio,qemu
Platform Features???????? : timer,mfdeleg
Platform HART Count?????? : 1
Firmware Base???????????? : 0x80000000
Firmware Size???????????? : 104 KB
Runtime SBI Version?????? : 0.2

Domain0 Name????????????? : root
Domain0 Boot HART???????? : 0
Domain0 HARTs???????????? : 0*
Domain0 Region00????????? : 0x0000000080000000-0x000000008001ffff ()
Domain0 Region01????????? : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address????? : 0x0000000080200000
Domain0 Next Arg1???????? : 0x0000000082200000
Domain0 Next Mode???????? : S-mode
Domain0 SysReset????????? : yes

Boot HART ID????????????? : 0
Boot HART Domain????????? : root
Boot HART ISA???????????? : rv64imafdcsu
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 MHPM Count????? : 0
Boot HART MIDELEG???????? : 0x0000000000000222
Boot HART MEDELEG???????? : 0x000000000000b109


U-Boot 2021.01-rc2-00161-gf6cf78dc6a (Dec 02 2020 - 07:05:39 +0100)

CPU:?? rv64imafdcsu
Model: riscv-virtio,qemu
DRAM:? 1 GiB
Loading Environment from FAT... OK
In:??? uart at 10000000
Out:?? uart at 10000000
Err:?? uart at 10000000
Net:?? No ethernet found.
Hit any key to stop autoboot:? 0
bootcmd=printenv bootcmd; fatload virtio 0:1 0x84000000 uImage; fatload
virtio 0:1 0x88000000 dtb; bootm 0x84000000 - 0x88000000
17704512 bytes read in 39 ms (432.9 MiB/s)
3618 bytes read in 1 ms (3.5 MiB/s)
## Booting kernel from Legacy Image at 84000000 ...
?? Image Name:?? Linux
?? Image Type:?? RISC-V Linux Kernel Image (uncompressed)
?? Data Size:??? 17704448 Bytes = 16.9 MiB
?? Load Address: 80200000
?? Entry Point:? 80200000
?? Verifying Checksum ... OK
## Flattened Device Tree blob at 88000000
?? Booting using the fdt blob at 0x88000000
?? Loading Kernel Image
?? Using Device Tree in place@0000000088000000, end 0000000088003e21

Starting kernel ...


... and that's all I get, no further output. I'm not sure my dtb file is
suitable though. I'm surprised there is no DTS file for the riscv64
"virt" board emulated by QEMU in the Linux kernel sources, as U-Boot
will refuse to boot Linux without one.

Note that in U-Boot, the bootargs environment is set to:
bootargs=console=ttyS0

I'll be interested in your advise, if you already managed to do
something like this.

Cheers,

Michael.

-- 
Michael Opdenacker, CEO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[sw-dev] Booting Linux from U-Boot in qemu-system-riscv64?

[Anup Patel]

Hi Michael,

Set bootargs to "root=/dev/vda2 rootwait console=ttyS0 earlycon=sbi" in
U-Boot before doing bootm

Regards,
Anup

On Wed, 2 Dec, 2020, 12:51 Michael Opdenacker, <
michael.opdenacker@bootlin.com> wrote:

> Greetings,
>
> To prepare an embedded Linux demo (on RiscV), I'm trying to boot Linux
> from U-Boot in qemu-system-riscv64, using the "virt" emulated machine...
> Note that I'm using QEMU 5.0.
>
> The well documented way to boot Linux works:
>
> In Linux master:
> CROSS_COMPILE=riscv64-linux-gnu- (toolchain built by Buildroot)
> ARCH=riscv
> make defconfig
> make
>
> In opensbi:
> make PLATFORM=generic FW_PAYLOAD_PATH=../linux/arch/riscv/boot/Image
>
> Running QEMU:
> qemu-system-riscv64 -nographic  -machine virt -kernel
> opensbi/build/platform/generic/firmware/fw_payload.elf -append
> "console=ttyS0"
>
> I can also boot U-Boot, but cannot manage to boot the Linux kernel with it:
>
> In U-Boot mainline:
>
> CROSS_COMPILE=riscv64-linux-gnu-
> make qemu-riscv64_smode_defconfig
> Modify the environment:
> - Unset CONFIG_ENV_IS_NOWHERE
> - CONFIG_ENV_IS_IN_FAT=y
> - CONFIG_ENV_FAT_INTERFACE="virtio"
> - CONFIG_ENV_FAT_DEVICE_AND_PART="0:1"
> - CONFIG_ENV_FAT_FILE="uboot.env"
> make
>
> Note that having U-Boot in "S" mode seems to be required to boot Linux.
> If U-Boot is in "M" mode, it works, but there are faults (as expected)
> when trying to execute Linux.
>
> In opensbi:
> make PLATFORM=generic FW_PAYLOAD_PATH=../u-boot/u-boot.bin
>
> I then prepared a disk.img image with a first FAT partition containing:
> - A "dtb" file captured from the first Linux boot (from /sys/firmware/fdt)
> - A "uImage" file made from the command:
> mkimage -A riscv -O linux -C none  -T kernel -a 80200000 -e 80200000 -n
> "Linux" -d arch/riscv/boot/Image uImage
>
> Then I'm starting QEMU as follows:
>
> qemu-system-riscv64 -m 1G -nographic  -machine virt -bios
> opensbi/build/platform/generic/firmware/fw_payload.bin -device
> virtio-blk-device,drive=hd0 -drive file=disk.img,format=raw,id=hd0
>
> OpenSBI v0.8-58-g781cafd
>    ____                    _____ ____ _____
>   / __ \                  / ____|  _ \_   _|
>  | |  | |_ __   ___ _ __ | (___ | |_) || |
>  | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
>  | |__| | |_) |  __/ | | |____) | |_) || |_
>   \____/| .__/ \___|_| |_|_____/|____/_____|
>         | |
>         |_|
>
> Platform Name             : riscv-virtio,qemu
> Platform Features         : timer,mfdeleg
> Platform HART Count       : 1
> Firmware Base             : 0x80000000
> Firmware Size             : 104 KB
> Runtime SBI Version       : 0.2
>
> Domain0 Name              : root
> Domain0 Boot HART         : 0
> Domain0 HARTs             : 0*
> Domain0 Region00          : 0x0000000080000000-0x000000008001ffff ()
> Domain0 Region01          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
> Domain0 Next Address      : 0x0000000080200000
> Domain0 Next Arg1         : 0x0000000082200000
> Domain0 Next Mode         : S-mode
> Domain0 SysReset          : yes
>
> Boot HART ID              : 0
> Boot HART Domain          : root
> Boot HART ISA             : rv64imafdcsu
> 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 MHPM Count      : 0
> Boot HART MIDELEG         : 0x0000000000000222
> Boot HART MEDELEG         : 0x000000000000b109
>
>
> U-Boot 2021.01-rc2-00161-gf6cf78dc6a (Dec 02 2020 - 07:05:39 +0100)
>
> CPU:   rv64imafdcsu
> Model: riscv-virtio,qemu
> DRAM:  1 GiB
> Loading Environment from FAT... OK
> In:    uart at 10000000
> Out:   uart at 10000000
> Err:   uart at 10000000
> Net:   No ethernet found.
> Hit any key to stop autoboot:  0
> bootcmd=printenv bootcmd; fatload virtio 0:1 0x84000000 uImage; fatload
> virtio 0:1 0x88000000 dtb; bootm 0x84000000 - 0x88000000
> 17704512 bytes read in 39 ms (432.9 MiB/s)
> 3618 bytes read in 1 ms (3.5 MiB/s)
> ## Booting kernel from Legacy Image at 84000000 ...
>    Image Name:   Linux
>    Image Type:   RISC-V Linux Kernel Image (uncompressed)
>    Data Size:    17704448 Bytes = 16.9 MiB
>    Load Address: 80200000
>    Entry Point:  80200000
>    Verifying Checksum ... OK
> ## Flattened Device Tree blob at 88000000
>    Booting using the fdt blob at 0x88000000
>    Loading Kernel Image
>    Using Device Tree in place at 0000000088000000, end 0000000088003e21
>
> Starting kernel ...
>
>
> ... and that's all I get, no further output. I'm not sure my dtb file is
> suitable though. I'm surprised there is no DTS file for the riscv64
> "virt" board emulated by QEMU in the Linux kernel sources, as U-Boot
> will refuse to boot Linux without one.
>
> Note that in U-Boot, the bootargs environment is set to:
> bootargs=console=ttyS0
>
> I'll be interested in your advise, if you already managed to do
> something like this.
>
> Cheers,
>
> Michael.
>
> --
> Michael Opdenacker, CEO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
> --
> You received this message because you are subscribed to the Google Groups
> "RISC-V SW Dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sw-dev+unsubscribe at groups.riscv.org.
> To view this discussion on the web visit
> https://groups.google.com/a/groups.riscv.org/d/msgid/sw-dev/6071db20-58af-55d3-5bec-8561d18a1707%40bootlin.com
> .
>

[sw-dev] Booting Linux from U-Boot in qemu-system-riscv64?

[Michael Opdenacker]

Hi Anup,

On 12/2/20 3:28 PM, Anup Patel wrote:
> root=/dev/vda2 rootwait console=ttyS0 earlycon=sbi


Many thanks for the "earlycon=sbi" tip. It doesn't solve the problem yet
but definitely helps to get further details:

[??? 0.000000] Linux version 5.10.0-rc5-00357-gaae5ab854e38
(mike at mike-laptop) (riscv64-linux-gnu-gcc (Ubuntu 9.3.0-17ubuntu1~20.04)
9.3.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #11 SMP Tue Dec 1 07:13:44
CET 2020
[??? 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
[??? 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
[??? 0.000000] printk: bootconsole [sbi0] enabled
[??? 0.000000] efi: UEFI not found.
[??? 0.000000] Zone ranges:
[??? 0.000000]?? DMA32??? [mem 0x0000000080200000-0x0000000081ffffff]
[??? 0.000000]?? Normal?? empty
[??? 0.000000] Movable zone start for each node
[??? 0.000000] Early memory node ranges
[??? 0.000000]?? node?? 0: [mem 0x0000000080200000-0x0000000081ffffff]
[??? 0.000000] Initmem setup node 0 [mem
0x0000000080200000-0x0000000081ffffff]
[??? 0.000000] Unable to handle kernel paging request at virtual address
ffffffe007e00001
[??? 0.000000] Oops [#1]
[??? 0.000000] Modules linked in:
[??? 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted
5.10.0-rc5-00357-gaae5ab854e38 #11
[??? 0.000000] epc: ffffffe0004a8b38 ra : ffffffe000021cb8 sp :
ffffffe001003f60
[??? 0.000000]? gp : ffffffe0010e1fb0 tp : ffffffe00100bd40 t0 :
ffffffe001d8efc0
[??? 0.000000]? t1 : 0000000081f8efc0 t2 : 2d656b696d40656b s0 :
ffffffe001003f80
[??? 0.000000]? s1 : ffffffe007e00000 a0 : ffffffe007e00000 a1 :
ffffffe001d8ef80
[??? 0.000000]? a2 : 0000000000000000 a3 : 0000000000000000 a4 :
0000000000000000
[??? 0.000000]? a5 : ffffffdf7fe00000 a6 : ffffffe0010104b8 a7 :
0000000000000030
[??? 0.000000]? s2 : ffffffe0010e30a8 s3 : 0000000000000003 s4 :
fffffffffffffff3
[??? 0.000000]? s5 : 00000000bffe1c70 s6 : 0000000000000000 s7 :
0000000000000000
[??? 0.000000]? s8 : 00000000bff6a042 s9 : 0000000080200000 s10:
0000000000000000
[??? 0.000000]? s11: 0000000000000000 t3 : 0000000000000018 t4 :
0000000000000001
[??? 0.000000]? t5 : 0000000000000018 t6 : 0000000001e00000
[??? 0.000000] status: 0000000000000100 badaddr: ffffffe007e00001 cause:
000000000000000d
[??? 0.000000] random: get_random_bytes called from
print_oops_end_marker+0x22/0x44 with crng_init=0
[??? 0.000000] ---[ end trace 0000000000000000 ]---
[??? 0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[??? 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill
the idle task! ]---


Now I guess I can compare with the run in which the kernel is directly
started without U-Boot...

Suggestions welcome of course...

Thanks again,

Michael.

-- 
Michael Opdenacker, CEO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com