Multicore UEFI in QEMU?

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HSE

Joined: 13 Jan 2019
Posts: 15

HSE 27 Apr 2022, 16:20

Hi all!

It's posible to do that? I'm failing to run QEMU with more than one core with OVMF_CODE_4M.fd or edk2-x86_64-code.fd

For example:

Quote:

"X:\Program Files\qemu\qemu-system-x86_64w.exe" ^
-nodefaults ^
-cpu qemu64 -smp 4 -vga std -machine q35,smm=on ^
-device qemu-xhci -device usb-mouse -device usb-kbd ^
-drive file=firmware\OVMF_amd64\OVMF_CODE_4M.fd,if=pflash,format=raw,unit=0,readonly=on ^
-drive file=firmware\OVMF_amd64\OVMF_VARS_4M.fd,if=pflash,format=raw,unit=1 ^
-drive file=fat:rw:e:\,index=1,media=disk,if=virtio,format=raw

Thanks in advance, HSE.

27 Apr 2022, 16:20

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 27 Apr 2022, 21:35

Are you using something like:
https://github.com/tianocore/edk2/blob/master/UefiCpuPkg/Application/Cpuid/

... to display CPU information, or have you written your own program to detect processors?

If QEMU fails to run, it usually displays an error message.

What are your tools telling you?

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

27 Apr 2022, 21:35

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 27 Apr 2022, 22:03

Not like that.

I'm using EFI_MP_SERVICES Protocol. Same program from boot detected 8 CPU (they are 4 cores with hyperthread) but in QEMU detect only one. There are no errors.

[Just some hours ago I adapted your UINT64__Baseform proc to unicode. Very interesting. I need that exactly to show this numbers (until now I loaded to FPU, not so elegant nor fast).]

27 Apr 2022, 22:03

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 27 Apr 2022, 22:17

Have you tried specifying the exact topology you'd like to test?

Code:

-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]

QEMU behavior changes with different versions - it is best to be explicit. Current default is just to create cores and not socketed CPUs.

https://www.qemu.org/docs/master/system/qemu-manpage.html

27 Apr 2022, 22:17

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 28 Apr 2022, 00:00

Now better:

Code:

-smp sockets=1,dies=1,cpus=8,maxcpus=8,clusters=2,cores=2,threads=2

No error, just don't run.

Code:

-smp sockets=1,dies=1,cpus=8,maxcpus=8,cores=4,threads=2

Run but nothing change, only one cpu.

28 Apr 2022, 00:00

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 28 Apr 2022, 11:07

Quote:

For a particular machine type board, an expected CPU topology hierarchy
can be defined through the supported sub-option. Unsupported parameters
can also be provided in addition to the sub-option, but their values
must be set as 1 in the purpose of correct parsing.

These statements on the QEMU -help makes me think the problem might be a limitation of the machine specification.

Does your test program work on real hardware? It would help to insure it's a configuration problem with QEMU.

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

28 Apr 2022, 11:07

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 28 Apr 2022, 12:09

Some weeks ago (when was not so relevant Very Happy

) I read somewhere that multicore depends on machine used. But I don't know if x86_64 machines can do that. Multicore examples I found are ARM, or about images with OS.

The program work in real hardware.

Relevant lines are very simple:

Code:

  mov rax, pBootServices
  invoke [rax].EFI_BOOT_SERVICES.LocateProtocol, ADDR EFI_MP_SERVICES_PROTOCOL_GUID, NULL, ADDR MpProtocol

  mov rcx, MpProtocol
  invoke [rcx].MP_SERVICES.GetNumberOfProcessors, MpProtocol, addr ProcessorNum, addr EnabledProcessorNum

Description:	Have some precarious timing (a little incomplete) and processors detection, wich is the relevant part here	Download
Filename:	CoreUEFI1.zip
Filesize:	5.33 KB
Downloaded:	416 Time(s)

28 Apr 2022, 12:09

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 28 Apr 2022, 13:30

Ah, found a better way to confirm QEMU cpus:

Add command line option "-monitor vc"

During emulation press <Ctrl><Alt><2> to enter monitor mode.

Type command: "info cpus"

... and sure enough there they are. (Here they are - I hope there they are, lol.)

28 Apr 2022, 13:30

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 28 Apr 2022, 13:43

Perfectly!!

Only one have an asterisk.
Then is a limitation of UEFI emulation ¿?

28 Apr 2022, 13:43

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 28 Apr 2022, 13:53

Maybe, but I always blame myself first.

The EFI app crashed on my end. So, I would try to debug or implement in another way. If that fails too, then try another firmware build. Actually, trying another firmware is quite easy - if that gives same results then the app code is probably in error.

28 Apr 2022, 13:53

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 28 Apr 2022, 14:34

Must crash after show processors. I rename BOOTX64 and use like boot file.

28 Apr 2022, 14:34

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 01 May 2022, 22:34

No luck with QEMU, fortunately worked in VirtualBox, but it's not the same.

Thanks

01 May 2022, 22:34

bitRAKE

Joined: 21 Jul 2003
Posts: 4073
Location: vpcmpistri

bitRAKE 02 May 2022, 01:17

What version of QEMU are you using?

7.0 was just released, but it's very buggy in Windows, in my experience.

_________________
¯\(°_o)/¯ “languages are not safe - uses can be” Bjarne Stroustrup

02 May 2022, 01:17

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 02 May 2022, 13:36

bitRAKE wrote:

What version of QEMU are you using?

7.0 was just released, but it's very buggy in Windows, in my experience.

Package is 6.2, but qemu-system-x86_64 is 5.2.

Probably machine is too old:

Code:

q35                  Standard PC (Q35 + ICH9, 2009) (alias of pc-q35-5.2)

02 May 2022, 13:36

I

Joined: 19 May 2022
Posts: 58

I 09 Jul 2022, 00:41

It's a bit late but what worked for me using a similar command line was adding option "-accel kvm", otherwise only single core .

09 Jul 2022, 00:41

HSE

Joined: 13 Jan 2019
Posts: 15

HSE 09 Jul 2022, 03:52

kvm is not valid. Thanks anyway.

09 Jul 2022, 03:52

I

Joined: 19 May 2022
Posts: 58

I 10 Jul 2022, 03:21

You can find out what can be used for your system with "qemu-system-x86_64.exe -accel help"

The default accelerator tcg seems somewhat limited
https://wiki.qemu.org/Documentation/Platforms

Windows HyperVisor - whpx (only some Windows OS's)
Intel HAXM - hax (Only Windows Intel and needs HAXM installed)

Be aware trying might end up being more trouble than it's worth.

10 Jul 2022, 03:21

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