Qemu-system-ppc built from current master can no longer run Fedora 12 ppc as guest. (This the only ppc distro I tested.) Host is Fedora 34. Please see screen shot attached.
Booting from both an installation DVD and from an installed system fail.
compile qemu-system-ppc from current master and run:
-M mac99,via=pmu \
-m 1024 \
-L pc-bios \
-boot d \
-cdrom Fedora-12-ppc-DVD.iso \
I tracked the issue down to this commit:
8f0a4b6a9b40e18116a2bb6bbcc00feb8119c792 is the first bad commit
Author: Matheus Ferst <email@example.com
Date: Tue Jun 1 16:35:28 2021 -0300
target/ppc: Move cmp/cmpi/cmpl/cmpli to decodetree
Additionally, REQUIRE_64BIT when L=1 to match what is specified in The
Programming Environments Manual:
"For 32-bit implementations, the L field must be cleared, otherwise the
instruction form is invalid."
Some CPUs are known to deviate from this specification by ignoring the
L bit . The stricter behavior, however, can help users that test
software with qemu, making it more likely to detect bugs that would
otherwise be silent.
If deemed necessary, a future patch can adapt this behavior based on
the specific CPU model.
 The 601 manual is the only one I've found that explicitly states
that the L bit is ignored, but we also observe this behavior in a 7447A
Signed-off-by: Matheus Ferst <firstname.lastname@example.org
Reviewed-by: Richard Henderson <email@example.com
[dwg: Corrected whitespace error]
Signed-off-by: David Gibson <firstname.lastname@example.org
target/ppc/insn32.decode | 14 ++++++++
target/ppc/translate.c | 52 ------------------------------
target/ppc/translate/fixedpoint-impl.c.inc | 31 ++++++++++++++++++
3 files changed, 45 insertions(+), 52 deletions(-)