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).
    
    Signed-off-by: Mark Cave-Ayland <[email protected]>
    Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
    Link: 
https://lore.kernel.org/r/[email protected]
    Signed-off-by: Paolo Bonzini <[email protected]>

and keeps the dumb part.  Matches the commit message.

Reviewed-by: Markus Armbruster <[email protected]>


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