On 10/07/2025 11:46, Philippe Mathieu-Daudé wrote:
On 10/7/25 10:52, Mark Cave-Ayland wrote:
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 -cpu max then the
"best"
32-bit CPU is used (in this case the pentium3).
Signed-off-by: Mark Cave-Ayland <mark.caveayl...@nutanix.com>
---
hw/i386/pc_piix.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index ea7572e783..67c52d79b2 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -418,6 +418,18 @@ static void pc_set_south_bridge(Object *obj, int
value, Error **errp)
#ifdef CONFIG_ISAPC
static void pc_init_isa(MachineState *machine)
{
+ /*
+ * 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");
Please warn() the user, otherwise:
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
+ }
+
pc_init1(machine, NULL);
}
Thanks! That sounds reasonable - I can add that in v5.
ATB,
Mark.
