On Fri, Sep 26, 2025 at 01:36:25PM +0200, Markus Armbruster wrote: > Mark Cave-Ayland <[email protected]> writes: > > > Following recent discussions on the mailing list, it has been decided > > that instead of mapping -cpu host and -cpu max to a suitable 32-bit x86 CPU, > > it is preferable to disallow them and use the existing valid_cpu_types > > validation logic so that an error is returned to the user instead. > > > > Signed-off-by: Mark Cave-Ayland <[email protected]> > > --- > > hw/i386/isapc.c | 27 --------------------------- > > 1 file changed, 27 deletions(-) > > > > diff --git a/hw/i386/isapc.c b/hw/i386/isapc.c > > index 44f4a44672..6c35a397df 100644 > > --- a/hw/i386/isapc.c > > +++ b/hw/i386/isapc.c > > @@ -41,31 +41,6 @@ static void pc_init_isa(MachineState *machine) > > DriveInfo *hd[MAX_IDE_BUS * MAX_IDE_DEVS]; > > int i; > > > > - /* > > - * There is a small chance that someone unintentionally passes "-cpu > > max" > > - * for the isapc machine, which will provide a much more modern 32-bit > > - * CPU than would be expected for an ISA-era PC. If the "max" cpu type > > has > > - * been specified, choose the "best" 32-bit cpu possible which we > > consider > > - * be the pentium3 (deliberately choosing an Intel CPU given that the > > - * default 486 CPU for the isapc machine is also an Intel CPU). > > - */ > > - if (!strcmp(machine->cpu_type, X86_CPU_TYPE_NAME("max"))) { > > - machine->cpu_type = X86_CPU_TYPE_NAME("pentium3"); > > - warn_report("-cpu max is invalid for isapc machine, using > > pentium3"); > > - } > > - > > - /* > > - * Similarly if someone unintentionally passes "-cpu host" for the > > isapc > > - * machine then display a warning and also switch to the "best" 32-bit > > - * cpu possible which we consider to be the pentium3. This is because > > any > > - * host CPU will already be modern than this, but it also ensures any > > - * newer CPU flags/features are filtered out for older guests. > > - */ > > - if (!strcmp(machine->cpu_type, X86_CPU_TYPE_NAME("host"))) { > > - machine->cpu_type = X86_CPU_TYPE_NAME("pentium3"); > > - warn_report("-cpu host is invalid for isapc machine, using > > pentium3"); > > - } > > - > > if (machine->ram_size > 3.5 * GiB) { > > error_report("Too much memory for this machine: %" PRId64 " MiB, " > > "maximum 3584 MiB", machine->ram_size / MiB); > > @@ -162,8 +137,6 @@ static void isapc_machine_options(MachineClass *m) > > X86_CPU_TYPE_NAME("pentium2"), > > X86_CPU_TYPE_NAME("pentium3"), > > X86_CPU_TYPE_NAME("qemu32"), > > - X86_CPU_TYPE_NAME("max"), > > - X86_CPU_TYPE_NAME("host"), > > NULL > > }; > > PCMachineClass *pcmc = PC_MACHINE_CLASS(m); > > This reverts the "smart" part of recent > > commit e1e2909f8e74051a34a044940f90d4650b6e784a > Author: Mark Cave-Ayland <[email protected]> > Date: Thu Aug 28 12:09:44 2025 +0100 > > hw/i386/pc_piix.c: restrict isapc machine to 32-bit CPUs > > The isapc machine represents a legacy ISA PC with a 486 CPU. Whilst it is > possible to specify any CPU via -cpu on the command line, it makes no > sense to allow modern 64-bit CPUs to be used. > > Restrict the isapc machine to the available 32-bit CPUs, taking care to > handle the case where if a user inadvertently uses either -cpu max or > -cpu host then the "best" 32-bit CPU is used (in this case the pentium3).
What is written here made sense from the POV of use of isapc with qemu-system-x86_64, but in qemu-system-i686, both 'max' and 'host' where already 32-bit CPUs IIUC. Both this original patch and the new patch block them from being used in qemu-system-i686 which feels wrong given the justification above. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
