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[iobuf] Allow allocation of I/O buffers with a specified alignment offset 

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2012-08-29 16:13:56 +01:00
parent e2becce186
commit 96be171be5
2 changed files with 32 additions and 15 deletions
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45
src/core/iobuf.c
View File

@ -32,31 +32,25 @@ FILE_LICENCE ( GPL2_OR_LATER );
*/ */
/** /**
* Allocate I/O buffer * Allocate I/O buffer with specified alignment and offset
* *
* @v len Required length of buffer * @v len Required length of buffer
* @v align Physical alignment
* @v offset Offset from physical alignment
* @ret iobuf I/O buffer, or NULL if none available * @ret iobuf I/O buffer, or NULL if none available
* *
* The I/O buffer will be physically aligned to a multiple of * @c align will be rounded up to the nearest power of two.
* @c IOBUF_SIZE.
*/ */
struct io_buffer * alloc_iob ( size_t len ) { struct io_buffer * alloc_iob_raw ( size_t len, size_t align, size_t offset ) {
struct io_buffer *iobuf; struct io_buffer *iobuf;
size_t align;
void *data; void *data;
/* Pad to minimum length */
if ( len < IOB_ZLEN )
len = IOB_ZLEN;
/* Align buffer length to ensure that struct io_buffer is aligned */ /* Align buffer length to ensure that struct io_buffer is aligned */
len = ( len + __alignof__ ( *iobuf ) - 1 ) & len = ( len + __alignof__ ( *iobuf ) - 1 ) &
~( __alignof__ ( *iobuf ) - 1 ); ~( __alignof__ ( *iobuf ) - 1 );
/* Align buffer on its own size to avoid potential problems /* Round up alignment to the nearest power of two */
* with boundary-crossing DMA. align = ( 1 << fls ( align - 1 ) );
*/
align = ( 1 << fls ( len - 1 ) );
/* Allocate buffer plus descriptor as a single unit, unless /* Allocate buffer plus descriptor as a single unit, unless
* doing so will push the total size over the alignment * doing so will push the total size over the alignment
@ -65,7 +59,8 @@ struct io_buffer * alloc_iob ( size_t len ) {
if ( ( len + sizeof ( *iobuf ) ) <= align ) { if ( ( len + sizeof ( *iobuf ) ) <= align ) {
/* Allocate memory for buffer plus descriptor */ /* Allocate memory for buffer plus descriptor */
data = malloc_dma ( len + sizeof ( *iobuf ), align ); data = malloc_dma_offset ( len + sizeof ( *iobuf ), align,
offset );
if ( ! data ) if ( ! data )
return NULL; return NULL;
iobuf = ( data + len ); iobuf = ( data + len );
@ -73,7 +68,7 @@ struct io_buffer * alloc_iob ( size_t len ) {
} else { } else {
/* Allocate memory for buffer */ /* Allocate memory for buffer */
data = malloc_dma ( len, align ); data = malloc_dma_offset ( len, align, offset );
if ( ! data ) if ( ! data )
return NULL; return NULL;
@ -92,6 +87,26 @@ struct io_buffer * alloc_iob ( size_t len ) {
return iobuf; return iobuf;
} }
/**
* Allocate I/O buffer
*
* @v len Required length of buffer
* @ret iobuf I/O buffer, or NULL if none available
*
* The I/O buffer will be physically aligned on its own size (rounded
* up to the nearest power of two).
*/
struct io_buffer * alloc_iob ( size_t len ) {
/* Pad to minimum length */
if ( len < IOB_ZLEN )
len = IOB_ZLEN;
/* Align buffer on its own size to avoid potential problems
* with boundary-crossing DMA.
*/
return alloc_iob_raw ( len, len, 0 );
}
/** /**
* Free I/O buffer * Free I/O buffer

2
src/include/ipxe/iobuf.h
View File

@ -210,6 +210,8 @@ static inline void iob_populate ( struct io_buffer *iobuf,
(iobuf) = NULL; \ (iobuf) = NULL; \
__iobuf; } ) __iobuf; } )
extern struct io_buffer * __malloc alloc_iob_raw ( size_t len, size_t align,
size_t offset );
extern struct io_buffer * __malloc alloc_iob ( size_t len ); extern struct io_buffer * __malloc alloc_iob ( size_t len );
extern void free_iob ( struct io_buffer *iobuf ); extern void free_iob ( struct io_buffer *iobuf );
extern void iob_pad ( struct io_buffer *iobuf, size_t min_len ); extern void iob_pad ( struct io_buffer *iobuf, size_t min_len );