David S. Miller wrote:
From: "Randy.Dunlap" <[EMAIL PROTECTED]>
Date: Mon, 15 May 2006 08:02:58 -0700
-#define NETDEV_ALIGN 32
+#define NETDEV_ALIGN L1_CACHE_BYTES
#define NETDEV_ALIGN_CONST (NETDEV_ALIGN - 1)
I don't know about the fixed value of 32, but if this patch is
accepted, I'd prefer NETDEV_ALIGN_MASK instead of NETDEV_ALIGN_CONST.
The reason it's 32 is that old drivers depended on the
struct being at least 32-byte aligned because they would
embed structures DMA'd to/from the card in their private
area and just assumed that would be aligned enough for
the card's restrictions.
So setting it to L1_CACHE_BYTES would be wrong, because if
that happens to be less than 32 it would violate said
assumption which we are catering to.
How about:
#define NETDEV_ALIGN_MIN 32
#if L1_CACHE_BYTES > NETDEV_ALIGN_MIN
# define NETDEV_ALIGN L1_CACHE_BYTES
#else
# define NETDEV_ALIGN NETDEV_ALIGN_MIN
#endif
rick jones
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