[Qemu-devel] [PATCH] target-i386: Enhance the stub for kvm_arch_get_supported_cpuid()

[Kamil Rytarowski]

This improves the commit:
"target-i386: Fix build by providing stub kvm_arch_get_supported_cpuid()"
r. 2140cfa51d59177815f5b82e94ac48fb24909aba

Clang/LLVM on NetBSD with enabled optimization cannot link
correct qemu program because of a missing symbol of
kvm_arch_get_supported_cpuid() in kvm-stubs.o used by executables.

There are more than a single one kvm-stub.c and several types
of possible programs such as bsd-user ones. the previous workaround
does not work reliably for all use-cases. Instead of reworking
the stubs and linking rules, move the workaround from a code that
depends on the __OPTIMIZE__ builtin compiler flag, build option (KVM),
compiler and arrangement of linking rules to a simple macro in a
shared header with all the users that defines fallback dummy
implementation, ignoring whether it is optimized out or not.

Signed-off-by: Kamil Rytarowski <address@hidden>
---
 include/sysemu/kvm.h   | 13 +++++++++++++
 target/i386/kvm-stub.c | 10 ----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index a6d1cd190f..93d3c0f0b3 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -459,8 +459,21 @@ int kvm_vm_check_extension(KVMState *s, unsigned int 
extension);
         kvm_vcpu_ioctl(cpu, KVM_ENABLE_CAP, &cap);                   \
     })
 
+#ifdef CONFIG_KVM
 uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
                                       uint32_t index, int reg);
+#else
+/*
+ * This function is only called inside conditionals which we
+ * rely on the compiler to optimize out when CONFIG_KVM is not
+ * defined.
+ */
+#define kvm_arch_get_supported_cpuid(a, b, c, d)                     \
+    ({                                                               \
+        abort();                                                     \
+        0;                                                           \
+    })
+#endif
 uint32_t kvm_arch_get_supported_msr_feature(KVMState *s, uint32_t index);
 
 
diff --git a/target/i386/kvm-stub.c b/target/i386/kvm-stub.c
index e7a673e5db..9ce8566700 100644
--- a/target/i386/kvm-stub.c
+++ b/target/i386/kvm-stub.c
@@ -29,16 +29,6 @@ bool kvm_enable_x2apic(void)
 {
     return false;
 }
-
-/* This function is only called inside conditionals which we
- * rely on the compiler to optimize out when CONFIG_KVM is not
- * defined.
- */
-uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
-                                      uint32_t index, int reg)
-{
-    abort();
-}
 #endif
 
 bool kvm_hv_vpindex_settable(void)
-- 
2.20.1