Re: PCI DMA to small buffers on cache-incoherent arch

[William Jhun <wjhun@ayrnetworks.com>]

On Mon, Jun 10, 2002 at 11:07:40AM -0700, William Jhun wrote:
> Perhaps provide macros in asm/pci.h that will:
> 
> - Take a buffer size and add an appropriate amount (one cache line for
>   alignment and the remainder to fill out the last cache line) to be
>   used for kmalloc(), etc, eg:

Err, I should say any case where the buffer may not be cache-aligned
(this would enable the use of DMA to stack...). For allocation routines
that give a cache-aligned buffer, this is obviously not needed (but
would just add one cacheline to the size).

> 
> #define DMA_SIZE_ROUNDUP(size) \
>    ((size + 2*SMP_CACHE_BYTES - 1) & ~(SMP_CACHE_BYTES - 1))
>