On Mon, 25 Aug 2025, Harsh Prateek Bora wrote:
On 8/25/25 17:52, Thomas Huth wrote:
On 25/08/2025 14.08, Harsh Prateek Bora wrote:
On 8/25/25 17:28, Thomas Huth wrote:
As I said, qemu-system-ppc64 is currently a full superset of qemu-system-
ppc. The ppc64 binary contains all the 32-bit code, you can perfectly run
a "g3beige" or "bamboo" machine with qemu-system-ppc64, too. By disabling
the ppe42 code in the ppc64 binary, this would now introduce an execption
to that unwritten rule, so I'd expect that we'd not rather want to do
this now.
My understanding is that above holds true only for default builds which
builds all targets. We certainly do not build 32 bit ppc code when using
--configure target-list=ppc64-softmmu. (we have ppc-softmmu for 32 bit
though)
We do build 32-bit machines in ppc64-softmmu but leave out 64-bit from
ppc-softmmu so it's only one way.
Just give it a try:
./configure --target-list=ppc64-softmmu --disable-docs
make -j$(nproc)
./qemu-system-ppc64 -M g3beige
... works perfectly fine for me.
This would work because the respective code is not restricted with #ifndef
TARGET_PPC64.
However, there are instance like below in hw/ppc/mac_oldworld.c:
static void heathrow_class_init(ObjectClass *oc, const void *data)
{
MachineClass *mc = MACHINE_CLASS(oc);
FWPathProviderClass *fwc = FW_PATH_PROVIDER_CLASS(oc);
mc->desc = "Heathrow based PowerMac";
mc->init = ppc_heathrow_init;
mc->block_default_type = IF_IDE;
/* SMP is not supported currently */
mc->max_cpus = 1;
#ifndef TARGET_PPC64
mc->is_default = true;
#endif
This is only because the default machine for ppc64-softmmu is different
than for ppc-softmmu as the 64-bit machines don't exist in ppc-softmmu but
ppc64-softmmu had different default machine before machines from
qemu-system-ppc got included in qemu-system-ppc64 so it kept that. (Looks
like the default used to be mac_newworld before commit 159f8286b760dea but
wasn't changed to match but to something else.) The default machines are
arbitrary, we could make "none" the default and always require users to
supply -machine but that would break existing command lines so this wasn't
done.
Similarly, we have multiple instances with #else block for #ifdef
TARGET_PPC64 which doesnt get compiled with ppc64-softmmu, but only with
ppc-softmmu meant for 32-bit targets. See target/ppc/excp_helper.c for
example.
This is again leaving out 64-bit code from ppc-softmmu but as Thomas says
32-bit machines are always included in qemu-softmmu-ppc64. I can't find
the commit which changed this, previously we had these to be separate and
since some types are different in ppc64-softmmu it wasn't clear if that
could cause any problems for 32-bit CPUs and machines so ppc-softmmu was
kept until that's cleaned up which never happened. There are also some
pecularities in some machines like mac_newworld that behaves differently
in qemu-system-ppc and qemu-system-ppc64 and the potentially lower
performance of qemu-system-ppc64 in emulating 32-bit machines which is why
we still have ppc-softmmu.
Regards,
BALATON Zoltan
regards,
Harsh
AFAIK we don't have a switch to disable 32-bit code in the ppc64 binary.
Thomas