.bmp files contain 32-bit integers aligned at offsets of +2, +6, et cetera within the bmp_header structure (see include/bmp_layout.h).
Support for gzip-compressed .bmp files is present in the cfb_console display subsystem by uncompressing them prior to use.
This patch forces the in-memory header to be aligned properly for these compressed images by extracting them to a 2-byte offset in the memory returned by malloc. Since malloc will always return a 4-byte aligned value, this forces the .bmp header fields to be naturally aligned on 4-byte addresses.
Refer to these files for more details: doc/README.displaying-bmps doc/README.arm-unaligned-accesses
Signed-off-by: Eric Nelson eric.nelson@boundarydevices.com --- Changes in V2: - re-worded the subject line - expanded and re-worded the commit message Changes in V3: - shortened the subject line - fixed multiline comment style - added patch history - sent with "In-Reply-To" header referring to V1 See also: V1: http://patchwork.ozlabs.org/patch/323243/ V2: http://patchwork.ozlabs.org/patch/325348/
drivers/video/cfb_console.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/video/cfb_console.c b/drivers/video/cfb_console.c index 6db4073..b52e9ed 100644 --- a/drivers/video/cfb_console.c +++ b/drivers/video/cfb_console.c @@ -1473,7 +1473,11 @@ int video_display_bitmap(ulong bmp_image, int x, int y) printf("Error: malloc in gunzip failed!\n"); return 1; } - if (gunzip(dst, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE, + /* + * NB: we need to force offset of +2 + * See doc/README.displaying-bmps + */ + if (gunzip(dst+2, CONFIG_SYS_VIDEO_LOGO_MAX_SIZE-2, (uchar *) bmp_image, &len) != 0) { printf("Error: no valid bmp or bmp.gz image at %lx\n", @@ -1489,7 +1493,7 @@ int video_display_bitmap(ulong bmp_image, int x, int y) /* * Set addr to decompressed image */ - bmp = (bmp_image_t *) dst; + bmp = (bmp_image_t *)(dst+2);
if (!((bmp->header.signature[0] == 'B') && (bmp->header.signature[1] == 'M'))) {
