Kernel panic during installation on AMD 7840HS with 780M iGPU

User Support Hardware Issues
21

It seems that the virtualbox manifestation of this problem often causes a freeze at the message freeing initrd memory but I guess this is just because the log level is not high enough (like for me it freezed at (XEN) Xen is relinquishing VGA console. before I increased the log level). I could only provide the above screenshot of error output from whonix startup in virtualbox by switching to rescue mode boot for whonix boot in virtualbox .

I will post a link to this thread on some forums where people are clueless about this issue.

22

From what I have read it seems that it is impossible to

  • Install QubesOS
  • Run Linux images in virtualbox on Windows host
  • Run Linux images in virtualbox on Linux host

on AMD CPUs 7840U, 7840HS, 7940HS (maybe whole 7040 generation?) as long as the QubesOS/Linux image kernel is not patched.

23

Interestingly some people are claiming the problem disappears after a BIOS update.

Unfortunately there is no new BIOS for me at the moment.

1 Like
24

From the mailing list there is a virtualbox command:

Are you a VirtualBox user with an Ryzen Zen 4 Mobile and
are affected by this division by 0? Well try:

vboxmanage setextradata $VM VBoxInternal/CPUM/HostCPUID/80000006/edx 0x02009140
(Where $VM is the target VM. Then just start the VM again, it just
should now run).

And indeed after running this command I can start the virtual box image that did not work before. So my question is:

Is there a similar command or configuration for xen that I can apply to override the HostCPUID/80000006/edx value to 0x02009140?

1 Like
25

Xen’s xl domain configuration file syntax states

cpuid=“LIBXL_STRING” or cpuid=[ “XEND_STRING”, “XEND_STRING” ]

Configure the value returned when a guest executes the CPUID instruction. Two versions of config syntax are recognized: libxl and xend.

Xend format consists of an array of one or more strings of the form “leaf:reg=bitstring,…”. e.g. (matching the libxl example above):

cpuid=["1:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx0,edx=xx0xxxxxxxxxxxxxxxxxxxxxxxxxxxxx", ...]

“leaf” is an integer, either decimal or hex with a “0x” prefix. e.g. to specify something in the AMD feature leaves, use “0x80000001:ecx=…”.

So I think a xen configuration equivalent to the above
vboxmanage setextradata $VM VBoxInternal/CPUM/HostCPUID/80000006/edx 0x02009140
should look like

cpuid=["0x80000006:edx=0x02009140"]

But where do I place this? I am almost there please help me what I should do with this xen cpuid configuration string.

26

Hi. Have you resolved the issue? Looking forward to buy a 7840 lenovo laptop too

27

Can confirm 7940HS working. I did need to update the bios first though