Re: KVM-PR no longer works when compiled with new GCC compilers

On 23 April 2026 at 07:35 pm, John Paul Adrian Glaubitz wrote:
> Hi Christian,
>
> On Thu, 2026-04-23 at 18:50 +0200, Christian Zigotzky wrote:
>> On 02/10/25 08:37, Christian Zigotzky wrote:
>>> Hello,
>>>
>>> KVM-PR (-enable-kvm) doesn't work anymore on our PA Semi Nemo boards
>>> [1] if we compiled it with new GCC compilers.
>>> The VM can't boot. There aren't any messages on the serial console of
>>> QEMU.
>>>
>>> It boots without KVM-PR.
>>>
>>> Kernel config with new GCC compiler [2]:
>>>
>>> - CONFIG_CC_VERSION_TEXT="powerpc64-suse-linux-gcc (SUSE Linux) 11.5.0"
>>> - CONFIG_TARGET_CPU="power4"
>>> - CONFIG_TUNE_CPU="-mtune=power10"
>>>
>>> It works if I compile it with an old GCC compiler [3]:
>>>
>>> - CONFIG_CC_VERSION_TEXT="powerpc-linux-gnu-gcc (Ubuntu
>>> 9.4.0-1ubuntu1~20.04.1) 9.4.0"
>>> - CONFIG_TARGET_CPU="power4"
>>> - CONFIG_TUNE_CPU="-mtune=power9"
>>>
>>> Mtune changes to power9 automatically if I compiled it with an old GCC
>>> compiler. If I compile it with a new GCC compiler again it changes
>>> automatically to mtune=power10.
>>>
>>> Is mtune the reason of the KVM-PR issue? I think the issue is the new
>>> GCC. [4]
>>>
>>> Could you please check whether KVM-PR is compatible with new versions
>>> of GCC compilers?
>>>
>>> Thanks in advance,
>>>
>>> Christian
>>>
>>>
>>>
>>> [1] https://en.wikipedia.org/wiki/AmigaOne_X1000
>>>
>>> [2]
>>> https://github.com/chzigotzky/kernels/blob/45186997e6f347fd092f9ab629d62d6041426227/configs/x1000_defconfig
>>>
>>> [3]
>>> https://github.com/chzigotzky/kernels/blob/bc7a3e27b3fcdee52a8135435f02cf807a43872a/configs/x1000_defconfig
>>>
>>> [4] KVM-PR no longer works on an X1000 if the kernel has been compiled
>>> with a new GCC:
>>> https://forum.hyperion-entertainment.com/viewtopic.php?p=57146#p57146
>>>
>> Error messages (kvm-pr compiled with powerpc64-linux-gnu-gcc 14.1.1
>> 20240507 Red Hat Cross 14.1.1-1, GNU ld version 2.41-2.el10_0):
>>
>> [  800.274759] Couldn't emulate instruction 0x00000000 (op 0 xop 0)
>> [  800.274767] kvmppc_exit_pr_progint: emulation at 100 failed (00000000)
> I don't think "mtune=power9" or "mtune=power10" will work. Did you try "mtune=power4"?
>
> Adrian
>
I haven't tried it yet, but I'm going to give it a try.

Christian