Paul Goyette wrote:
> Any suggestions on how to ensure proper alignment? There doesn't seem
> to be any way to kmem_allocate() what alignment is needed... :) It
> seems to currently always provide 64-bit (8-byte) alignment, but the man
> page makes no guarantees.
>
> I guess I could allocate an extra 8 bytes, and then manipulate the
> returned address... But that just "feels wrong". :)
I meant alignment within the structures. Maybe "packing" might be
a better word. This helps for example with mixed 32-bit and 64-bit
emulations. If you look at your original struct sysctl_history_event:
struct sysctl_history_event {
struct timeval she_tv;
uint64_t she_callnumber;
uint64_t she_values[4];
The timeval is a structure with a 64-bit int for seconds and and
a 32-bit int for microseconds. With the following uint64_t some
architectures might pad out she_callnumber in the structure so that it's
on a 64-bit boundary while others will by happy with a 32-bit alignment
and not use any padding.
In short, just make sure everything in the struct packs nicely. :)
Cheers,
Simon.
