diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2007-07-31 16:17:13 -0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2007-07-31 16:18:05 -0400 |
| commit | ff659d13ed91dd0b237064aba91a5259f827aeb3 (patch) | |
| tree | 43f73d3d59ece433b3b463ec2c7d36d6a6d85fec /arch/i386/boot | |
| parent | 8b608d2f5a1b3552363a3161566645a409ff8530 (diff) | |
[x86 setup] EDD: Fix the computation of the MBR sector buffer
Some BIOSes require that sector buffers not cross 64K
boundaries. As a result, we compute a dynamic address on the
setup heap. Unfortunately, this address computation was just
totally wrong.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/i386/boot')
| -rw-r--r-- | arch/i386/boot/edd.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/i386/boot/edd.c b/arch/i386/boot/edd.c index 25a282494f4..77d92daf792 100644 --- a/arch/i386/boot/edd.c +++ b/arch/i386/boot/edd.c @@ -72,17 +72,18 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei) u32 mbrsig; u32 buf_base, mbr_base; extern char _end[]; - static char mbr_buf[1024]; sector_size = ei->params.bytes_per_sector; if (!sector_size) sector_size = 512; /* Best available guess */ + /* Produce a naturally aligned buffer on the heap */ buf_base = (ds() << 4) + (u32)&_end; mbr_base = (buf_base+sector_size-1) & ~(sector_size-1); - mbrbuf_ptr = mbr_buf + (mbr_base-buf_base); + mbrbuf_ptr = _end + (mbr_base-buf_base); mbrbuf_end = mbrbuf_ptr + sector_size; + /* Make sure we actually have space on the heap... */ if (!(boot_params.hdr.loadflags & CAN_USE_HEAP)) return 0; if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr) |