Re: [Qemu-devel] [PATCH 02/10] compiler.h: add QEMU_CACHELINE + QEMU_ALIGN() + QEMU_CACHELINE_ALIGNED

[Peter Maydell]

On 5 April 2016 at 13:57, Lluís Vilanova <address@hidden> wrote:
> Emilio G Cota writes:
>
>> I'm assuming windows compilers don't support this attribute.
>> Signed-off-by: Emilio G. Cota <address@hidden>
>> ---
>>  include/qemu/compiler.h | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>
>> diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
>> index 8f1cc7b..fb946f1 100644
>> --- a/include/qemu/compiler.h
>> +++ b/include/qemu/compiler.h
>> @@ -41,6 +41,16 @@
>>  # define QEMU_PACKED __attribute__((packed))
>>  #endif
>
>> +#define QEMU_CACHELINE (64)
> [...]
>
> You should make this a value taken from configure. In linux you could use
> something like:
>
>   getconf LEVEL1_DCACHE_LINESIZE
>
> Or an equivalent program using sysconf(3) if getconf is not present.

The cache line size at compile time is not necessarily the cache
line size at runtime...

thanks
-- PMM