On 27 sep 2009, at 03:34, Ming Lei wrote:
It is very odd, and how can you see the alignment of kmalloc is
violated if CONFIG_DEBUG_SLAB=y?
I added
printk("%p\n", bulk_in_buffer);
and it printed ffff880011b7cdf0.
The size of the kmalloc was 512 bytes.
DMA transfer requires that the transfer buffer is cache aligned, or
else
your problem is understandable.
Yeah I have read that before. I don't get why cache alignment matters
though.
The buffer allocated by kmalloc should be cache aligned, and it is a
basic requirement for kmalloc in fact.
mm/slab.c:
* Usually, the kmalloc caches are cache_line_size() aligned, except
when
* DEBUG and FORCED_DEBUG are enabled, then they are BYTES_PER_WORD
aligned.
Joris.
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