Re: [Qemu-devel] [PATCH] target/i386/kvm.c: Don't mark cpuid_data as QEMU_PACKED

[Richard Henderson]

On 12/10/18 5:46 AM, Peter Maydell wrote:
> clang complains about taking the address of a packed
> member of a struct:
> 
> target/i386/kvm.c:1245:27: warning: taking address of packed member 'cpuid' 
> of class or structure '' may result in an unaligned pointer value 
> [-Waddress-of-packed-member]
>     c = cpuid_find_entry(&cpuid_data.cpuid, 1, 0);
>                           ^~~~~~~~~~~~~~~~
> target/i386/kvm.c:1297:31: warning: taking address of packed member 'cpuid' 
> of class or structure '' may result in an unaligned pointer value 
> [-Waddress-of-packed-member]
>         c = cpuid_find_entry(&cpuid_data.cpuid, kvm_base, 0);
>                               ^~~~~~~~~~~~~~~~
> 
> The kernel's definitions of struct kvm_cpuid2 and struct
> kvm_cpuid_entry2 are carefully set up with padding fields
> so that there is no between-struct padding anyway, so
> the QEMU_PACKED annotation is unnecessary and might result
> in the compiler generating worse code. Drop it, and instead
> assert at build time that there is no stray padding.
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  target/i386/kvm.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Reviewed-by: Richard Henderson <address@hidden>


r~