On Wed, Nov 15, 2017 at 09:23:33AM -0800, Song Liu wrote:
> Note: We use type __u64 for pointer probe_desc instead of __aligned_u64.
> The reason here is to avoid changing the size of struct perf_event_attr,
> and breaking new-kernel-old-utility scenario. To avoid alignment problem
> with the pointer, we will (in the following patches) copy probe_desc to
> __aligned_u64 before using it as pointer.
ISTR there are only relatively few architectures where __u64 and
__aligned_u64 are not the same thing.
The comment that goes with it seems to suggest i386 has short alignment
for u64 but my compiler says differently:
printf("%d, %d\n", sizeof(unsigned long long), __alignof__(unsigned
long long));
$ gcc -m32 -o align align.c && ./align
8, 8
