On 11/9/23 15:15, Philippe Mathieu-Daudé 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. This was previously documented in commit 2140cfa51d
("i386: Fix build by providing stub kvm_arch_get_supported_cpuid()").
Fix by partially reverting those commits, restoring a pair of stubs
for the unoptimized Clang builds.
Reported-by: Kevin Wolf <kwolf@xxxxxxxxxx>
Suggested-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
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 <philmd@xxxxxxxxxx>
---
target/i386/kvm/kvm-stub.c | 31 +++++++++++++++++++++++++++++++
target/i386/kvm/meson.build | 2 ++
2 files changed, 33 insertions(+)
create mode 100644 target/i386/kvm/kvm-stub.c
Patch superseded, see v3:
https://lore.kernel.org/qemu-devel/20230911142729.25548-1-philmd@xxxxxxxxxx/
