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

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

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

@ -210,6 +210,8 @@ static inline void iob_populate ( struct io_buffer *iobuf,
(iobuf) = NULL; \
__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 void free_iob ( struct io_buffer *iobuf );
extern void iob_pad ( struct io_buffer *iobuf, size_t min_len );