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author | Michael Brown | 2006-04-25 14:11:36 +0200 |
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committer | Michael Brown | 2006-04-25 14:11:36 +0200 |
commit | cf3783b4caf3551d6ebb153f5a93a8ed57035af1 (patch) | |
tree | 97ea2747009e223dd09c1f1ec9dec51ba028a5f6 /src | |
parent | Update to use POSIX-like API. (diff) | |
download | ipxe-cf3783b4caf3551d6ebb153f5a93a8ed57035af1.tar.gz ipxe-cf3783b4caf3551d6ebb153f5a93a8ed57035af1.tar.xz ipxe-cf3783b4caf3551d6ebb153f5a93a8ed57035af1.zip |
Actually, it's probably a good idea to have packet buffers avoid 4kB
crossings.
Diffstat (limited to 'src')
-rw-r--r-- | src/include/gpxe/pkbuff.h | 11 | ||||
-rw-r--r-- | src/net/pkbuff.c | 26 |
2 files changed, 30 insertions, 7 deletions
diff --git a/src/include/gpxe/pkbuff.h b/src/include/gpxe/pkbuff.h index 895367ae..646b540d 100644 --- a/src/include/gpxe/pkbuff.h +++ b/src/include/gpxe/pkbuff.h @@ -17,6 +17,17 @@ struct net_protocol; struct ll_protocol; +/** + * Packet buffer alignment + * + * Packet buffers allocated via alloc_pkb() are guaranteed to be + * physically aligned to this boundary. Some cards cannot DMA across + * a 4kB boundary. With a standard Ethernet MTU, aligning to a 2kB + * boundary is sufficient to guarantee no 4kB boundary crossings. For + * a jumbo Ethernet MTU, a packet may be larger than 4kB anyway. + */ +#define PKBUFF_ALIGN 2048 + /** A packet buffer * * This structure is used to represent a network packet within gPXE. diff --git a/src/net/pkbuff.c b/src/net/pkbuff.c index b9b6709b..c1a6b2f7 100644 --- a/src/net/pkbuff.c +++ b/src/net/pkbuff.c @@ -31,24 +31,36 @@ * * @v len Required length of buffer * @ret pkb Packet buffer, or NULL if none available + * + * The packet buffer will be physically aligned to a multiple of + * @c PKBUFF_SIZE. */ struct pk_buff * alloc_pkb ( size_t len ) { struct pk_buff *pkb = NULL; + void *data; + /* Align buffer length */ + len = ( len + __alignof__ ( *pkb ) - 1 ) & ~ __alignof__ ( *pkb ); + /* Allocate memory for buffer plus descriptor */ - pkb = malloc ( sizeof ( *pkb ) + len ); - if ( pkb ) { - pkb->head = pkb->data = pkb->tail = ( void * ) ( pkb + 1 ); - pkb->end = pkb->head + len; - } + data = malloc_dma ( len + sizeof ( *pkb ), PKBUFF_ALIGN ); + if ( ! data ) + return NULL; + + pkb = ( struct pk_buff * ) ( data + len ); + pkb->head = pkb->data = pkb->tail = data; + pkb->end = pkb; return pkb; } /** * Free packet buffer * - * @v pkb Packet buffer, or NULL + * @v pkb Packet buffer */ void free_pkb ( struct pk_buff *pkb ) { - free ( pkb ); + if ( pkb ) { + free_dma ( pkb->head, + ( pkb->end - pkb->head ) + sizeof ( *pkb ) ); + } } |