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[PATCH 1/2] i386: use better matching family/model/stepping for 'qemu64'


From: Daniel P . Berrangé
Subject: [PATCH 1/2] i386: use better matching family/model/stepping for 'qemu64' CPU
Date: Fri, 7 May 2021 14:36:49 +0100

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" },
+};
 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




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