Or instead of using linker behavior, maybe just change the #ifdef so it only applies when KVM is disabled. I didn't look at the code to see if this is possible, but it would be nice to avoid the very specific #ifdef condition in this patch.
Stefan On Mon, Sep 11, 2023, 07:15 Stefan Hajnoczi <[email protected]> wrote: > On Mon, 11 Sept 2023 at 06:39, Philippe Mathieu-Daudé <[email protected]> > wrote: > > > > Since commits 3adce820cf..ef1cf6890f, When building on > > a x86 host configured as: > > > > $ ./configure --cc=clang \ > > --target-list=x86_64-linux-user,x86_64-softmmu \ > > --enable-debug > > > > we get: > > > > [71/71] Linking target qemu-x86_64 > > FAILED: qemu-x86_64 > > /usr/bin/ld: libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o: in > function `cpu_x86_cpuid': > > cpu.c:(.text+0x1374): undefined reference to > `kvm_arch_get_supported_cpuid' > > /usr/bin/ld: libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o: in > function `x86_cpu_filter_features': > > cpu.c:(.text+0x81c2): undefined reference to > `kvm_arch_get_supported_cpuid' > > /usr/bin/ld: cpu.c:(.text+0x81da): undefined reference to > `kvm_arch_get_supported_cpuid' > > /usr/bin/ld: cpu.c:(.text+0x81f2): undefined reference to > `kvm_arch_get_supported_cpuid' > > /usr/bin/ld: cpu.c:(.text+0x820a): undefined reference to > `kvm_arch_get_supported_cpuid' > > /usr/bin/ld: > libqemu-x86_64-linux-user.fa.p/target_i386_cpu.c.o:cpu.c:(.text+0x8225): > more undefined references to `kvm_arch_get_supported_cpuid' follow > > clang: error: linker command failed with exit code 1 (use -v to see > invocation) > > ninja: build stopped: subcommand failed. > > > > '--enable-debug' disables optimizations (CFLAGS=-O0). > > > > While at this (un)optimization level GCC eliminate the > > following dead code: > > > > if (0 && foo()) { > > ... > > } > > > > Clang does not. Therefore restore a pair of stubs for > > unoptimized Clang builds. > > > > Reported-by: Kevin Wolf <[email protected]> > > Fixes: 3adce820cf ("target/i386: Remove unused KVM stubs") > > Fixes: ef1cf6890f ("target/i386: Allow elision of > kvm_hv_vpindex_settable()") > > Signed-off-by: Philippe Mathieu-Daudé <[email protected]> > > --- > > target/i386/kvm/kvm_i386.h | 21 ++++++++++++++++++--- > > 1 file changed, 18 insertions(+), 3 deletions(-) > > > > diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h > > index 55d4e68c34..0b62ac628f 100644 > > --- a/target/i386/kvm/kvm_i386.h > > +++ b/target/i386/kvm/kvm_i386.h > > @@ -32,7 +32,6 @@ > > > > bool kvm_has_smm(void); > > bool kvm_enable_x2apic(void); > > -bool kvm_hv_vpindex_settable(void); > > bool kvm_has_pit_state2(void); > > > > bool kvm_enable_sgx_provisioning(KVMState *s); > > @@ -41,8 +40,6 @@ bool kvm_hyperv_expand_features(X86CPU *cpu, Error > **errp); > > void kvm_arch_reset_vcpu(X86CPU *cs); > > void kvm_arch_after_reset_vcpu(X86CPU *cpu); > > void kvm_arch_do_init_vcpu(X86CPU *cs); > > -uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function, > > - uint32_t index, int reg); > > uint64_t kvm_arch_get_supported_msr_feature(KVMState *s, uint32_t > index); > > > > void kvm_set_max_apic_id(uint32_t max_apic_id); > > @@ -60,6 +57,10 @@ void kvm_put_apicbase(X86CPU *cpu, uint64_t value); > > > > bool kvm_has_x2apic_api(void); > > bool kvm_has_waitpkg(void); > > +bool kvm_hv_vpindex_settable(void); > > + > > +uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function, > > + uint32_t index, int reg); > > > > uint64_t kvm_swizzle_msi_ext_dest_id(uint64_t address); > > void kvm_update_msi_routes_all(void *private, bool global, > > @@ -76,6 +77,20 @@ typedef struct kvm_msr_handlers { > > bool kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr, > > QEMUWRMSRHandler *wrmsr); > > > > +#elif defined(__clang__) && !defined(__OPTIMIZE__) > > Another approach is a static library with a .o file containing the > stubs so the linker only includes it in the executable if the compiler > emitted the symbols. That way there is no need for defined(__clang__) > && !defined(__OPTIMIZE__) and it will work with other > compilers/optimization levels. It's more work to set up though. > > Reviewed-by: Stefan Hajnoczi <[email protected]> >
