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

[Christian Zigotzky <chzigotzky@xenosoft.de>]

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