Re: [PATCH-for-9.0 v2] hw/i386/pc: Deprecate 64-bit CPUs on ISA-only PC machine

Per Daniel suggestion [*]: > isapc could arguably be restricted to just 32-bit CPU models, > because we should not need it to support any feature that didn't > exist prior to circa 1995. eg refuse to start with isapc, if 'lm' > is present in the CPU model for example. Display a warning when such CPU is used: $ qemu-system-x86_64 -monitor stdio -S -M isapc -cpu Westmere qemu-system-x86_64: warning: Use of 64-bit CPU 'Westmere' is deprecated on the ISA-only PC machine QEMU 8.2.91 monitor - type 'help' for more information (qemu) q $ qemu-system-x86_64 -monitor stdio -S -M isapc -cpu athlon QEMU 8.2.91 monitor - type 'help' for more information (qemu) q [*] https://lore.kernel.org/qemu-devel/ZgQkS4RPmSt5Xa08@redhat.com/ Suggested-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; Signed-off-by: Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; --- docs/about/deprecated.rst | 7 +++++++ include/hw/i386/pc.h | 1 + hw/i386/pc_piix.c | 14 ++++++++++++++ 3 files changed, 22 insertions(+) diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index 7b548519b5..345c35507f 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -208,6 +208,13 @@ is no longer packaged in any distro making it harder to run the ``check-tcg`` tests. Unless we can improve the testing situation there is a chance the code will bitrot without anyone noticing. +64-bit (x86_64) CPUs on the ``isapc`` machine (since 9.0) +''''''''''''''''''''''''''''''''''''''''''''''''''''''''' + +The ``isapc`` machine aims to emulate old PC machine without PCI was +generalized, so hardware available around 1995, before 64-bit intel +CPUs were produced. + System emulator machines ------------------------ diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 27a68071d7..2d202b9549 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -96,6 +96,7 @@ struct PCMachineClass { const char *default_south_bridge; /* Compat options: */ + bool deprecate_64bit_cpu; /* Specific to the 'isapc' machine */ /* Default CPU model version. See x86_cpu_set_default_version(). */ int default_cpu_version; diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index 18ba076609..2e5b2efc33 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c @@ -182,7 +182,20 @@ static void pc_init1(MachineState *machine, const char *pci_type) } pc_machine_init_sgx_epc(pcms); + x86_cpus_init(x86ms, pcmc->default_cpu_version); + if (pcmc->deprecate_64bit_cpu) { + X86CPU *cpu = X86_CPU(first_cpu); + + if (cpu->env.features[FEAT_8000_0001_EDX] & CPUID_EXT2_LM) { + const char *cpu_type = object_get_typename(OBJECT(first_cpu)); + int cpu_len = strlen(cpu_type) - strlen(X86_CPU_TYPE_SUFFIX); + + warn_report("Use of 64-bit CPU '%.*s' is deprecated" + " on the ISA-only PC machine", + cpu_len, cpu_type); + } + } if (kvm_enabled()) { kvmclock_create(pcmc->kvmclock_create_always); @@ -918,6 +931,7 @@ static void isapc_machine_options(MachineClass *m) pcmc->gigabyte_align = false; pcmc->smbios_legacy_mode = true; pcmc->has_reserved_memory = false; + pcmc->deprecate_64bit_cpu = true; m->default_nic = "ne2k_isa"; m->default_cpu_type = X86_CPU_TYPE_NAME("486"); m->no_parallel = !module_object_class_by_name(TYPE_ISA_PARALLEL);