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

[Christian Zigotzky]

On 23/04/26 19:46, Christian Zigotzky wrote:
> 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
I compiled it with "mtune=power4" today but without any success.

Error messages:

[  800.274759] Couldn't emulate instruction 0x00000000 (op 0 xop 0)
[  800.274767] kvmppc_exit_pr_progint: emulation at 100 failed (00000000)

Christian

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