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Re: [PATCH 1/2] i386: use better matching family/model/stepping for 'qem
From: |
Eduardo Habkost |
Subject: |
Re: [PATCH 1/2] i386: use better matching family/model/stepping for 'qemu64' CPU |
Date: |
Wed, 26 May 2021 15:31:21 -0400 |
On Fri, May 07, 2021 at 02:36:49PM +0100, Daniel P. Berrangé wrote:
> The 'qemu64' CPUID currently reports a family/model/stepping that
> approximately corresponds to an AMD K7 vintage architecture.
> The K7 series predates the introduction of 64-bit support by AMD
> in the K8 series. This has been reported to lead to LLVM complaints
> about generating 64-bit code for a 32-bit CPU target
>
> LLVM ERROR: 64-bit code requested on a subtarget that doesn't support it!
>
> It appears LLVM looks at the family/model/stepping, despite qemu64
> reporting it is 64-bit capable.
>
> This patch changes 'qemu64' to report a CPUID with the family, model
> and stepping taken from a
>
> AMD Athlon(tm) 64 X2 Dual Core Processor 4000+
>
> which is one of the first 64-bit AMD CPUs.
>
> Closes https://gitlab.com/qemu-project/qemu/-/issues/191
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
> hw/i386/pc.c | 6 +++++-
> target/i386/cpu.c | 6 +++---
> 2 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 364816efc9..35d7a8122a 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -96,7 +96,11 @@
> #include "trace.h"
> #include CONFIG_DEVICES
>
> -GlobalProperty pc_compat_6_0[] = {};
> +GlobalProperty pc_compat_6_0[] = {
> + { "qemu64" "-" TYPE_X86_CPU, "family", "6" },
> + { "qemu64" "-" TYPE_X86_CPU, "model", "6" },
> + { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
I wish we could have done this using a new CPU model version, but
the new version wouldn't be very useful unless the default CPU
model version to CPU_VERSION_LATEST[1], so:
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
[1] We still can't do that without breaking libvirt expectations
about machine types.
> +};
> const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
>
> GlobalProperty pc_compat_5_2[] = {
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index ad99cad0e7..99caa3deae 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -1881,9 +1881,9 @@ static X86CPUDefinition builtin_x86_defs[] = {
> .name = "qemu64",
> .level = 0xd,
> .vendor = CPUID_VENDOR_AMD,
> - .family = 6,
> - .model = 6,
> - .stepping = 3,
> + .family = 15,
> + .model = 107,
> + .stepping = 1,
> .features[FEAT_1_EDX] =
> PPRO_FEATURES |
> CPUID_MTRR | CPUID_CLFLUSH | CPUID_MCA |
> --
> 2.31.1
>
--
Eduardo