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Actually, it's probably a good idea to have packet buffers avoid 4kB

crossings.
tags/v0.9.3
Michael Brown 18 anni fa
parent
commit
cf3783b4ca
2 ha cambiato i file con 30 aggiunte e 7 eliminazioni
  1. 11
    0
      src/include/gpxe/pkbuff.h
  2. 19
    7
      src/net/pkbuff.c

+ 11
- 0
src/include/gpxe/pkbuff.h Vedi File

17
 struct net_protocol;
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 struct net_protocol;
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 struct ll_protocol;
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 struct ll_protocol;
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19
 
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+/**
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+ * Packet buffer alignment
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+ *
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+ * Packet buffers allocated via alloc_pkb() are guaranteed to be
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+ * physically aligned to this boundary.  Some cards cannot DMA across
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+ * a 4kB boundary.  With a standard Ethernet MTU, aligning to a 2kB
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+ * boundary is sufficient to guarantee no 4kB boundary crossings.  For
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+ * a jumbo Ethernet MTU, a packet may be larger than 4kB anyway.
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+ */
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+#define PKBUFF_ALIGN 2048
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+
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 /** A packet buffer
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 /** A packet buffer
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  *
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  *
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  * This structure is used to represent a network packet within gPXE.
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  * This structure is used to represent a network packet within gPXE.

+ 19
- 7
src/net/pkbuff.c Vedi File

31
  *
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  *
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  * @v len	Required length of buffer
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  * @v len	Required length of buffer
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  * @ret pkb	Packet buffer, or NULL if none available
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  * @ret pkb	Packet buffer, or NULL if none available
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+ *
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+ * The packet buffer will be physically aligned to a multiple of
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+ * @c PKBUFF_SIZE.
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  */
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  */
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 struct pk_buff * alloc_pkb ( size_t len ) {
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 struct pk_buff * alloc_pkb ( size_t len ) {
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 	struct pk_buff *pkb = NULL;
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 	struct pk_buff *pkb = NULL;
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+	void *data;
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41
 
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+	/* Align buffer length */
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+	len = ( len + __alignof__ ( *pkb ) - 1 ) & ~ __alignof__ ( *pkb );
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+	
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 	/* Allocate memory for buffer plus descriptor */
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 	/* Allocate memory for buffer plus descriptor */
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-	pkb = malloc ( sizeof ( *pkb ) + len );
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-	if ( pkb ) {
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-		pkb->head = pkb->data = pkb->tail = ( void * ) ( pkb + 1 );
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-		pkb->end = pkb->head + len;
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-	}
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+	data = malloc_dma ( len + sizeof ( *pkb ), PKBUFF_ALIGN );
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+	if ( ! data )
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+		return NULL;
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+
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+	pkb = ( struct pk_buff * ) ( data + len );
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+	pkb->head = pkb->data = pkb->tail = data;
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+	pkb->end = pkb;
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 	return pkb;
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 	return pkb;
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 }
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 }
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 /**
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 /**
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  * Free packet buffer
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  * Free packet buffer
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  *
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  *
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- * @v pkb	Packet buffer, or NULL
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+ * @v pkb	Packet buffer
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  */
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  */
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 void free_pkb ( struct pk_buff *pkb ) {
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 void free_pkb ( struct pk_buff *pkb ) {
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-	free ( pkb );
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+	if ( pkb ) {
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+		free_dma ( pkb->head,
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+			   ( pkb->end - pkb->head ) + sizeof ( *pkb ) );
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+	}
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 }
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 }

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