diff options
| author | Kevin Wolf <mail@kevin-wolf.de> | 2013-06-23 22:07:44 +0200 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2013-06-28 14:01:52 -0500 |
| commit | 390fb6b47144adbad453cdf95c130854728c56f8 (patch) | |
| tree | d41e418a88f68e96457bea8b341fe46c019ea3af /pc-bios | |
| parent | 6bedfe94c96c5ba35fcb2a52b438fefcc682669e (diff) | |
multiboot: Don't forget last mmap entry
When the BIOS returns ebx = 0, the current entry is still valid and
needs to be included in the Multiboot memory map.
Fixing this meant that using bx as the entry index doesn't work any
more because it's 0 on the last entry (and it was SeaBIOS-specific
anyway), so the whole loop had to change a bit and should be more
generic as a result (ebx can be an arbitrary continuation number now,
and the entry size returned by the BIOS is used instead of hard-coding
20 bytes).
Signed-off-by: Kevin Wolf <mail@kevin-wolf.de>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1372018066-21822-2-git-send-email-mail@kevin-wolf.de
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'pc-bios')
| -rw-r--r-- | pc-bios/optionrom/multiboot.S | 35 |
1 files changed, 17 insertions, 18 deletions
diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S index 003bcfb49f..a0f3602956 100644 --- a/pc-bios/optionrom/multiboot.S +++ b/pc-bios/optionrom/multiboot.S @@ -89,17 +89,14 @@ run_multiboot: /* Initialize multiboot mmap structs using int 0x15(e820) */ xor %ebx, %ebx - /* mmap start after first size */ - movl $4, %edi + /* Start storing mmap data at %es:0 */ + xor %edi, %edi mmap_loop: + /* The multiboot entry size has offset -4, so leave some space */ + add $4, %di /* entry size (mmap struct) & max buffer size (int15) */ movl $20, %ecx - /* store entry size */ - /* old as(1) doesn't like this insn so emit the bytes instead: - movl %ecx, %es:-4(%edi) - */ - .dc.b 0x26,0x67,0x66,0x89,0x4f,0xfc /* e820 */ movl $0x0000e820, %eax /* 'SMAP' magic */ @@ -107,21 +104,23 @@ mmap_loop: int $0x15 mmap_check_entry: - /* last entry? then we're done */ + /* Error or last entry already done? */ jb mmap_done - and %bx, %bx - jz mmap_done - /* valid entry, so let's loop on */ mmap_store_entry: - /* %ax = entry_number * 24 */ - mov $24, %ax - mul %bx - mov %ax, %di + /* store entry size */ + /* old as(1) doesn't like this insn so emit the bytes instead: + movl %ecx, %es:-4(%edi) + */ + .dc.b 0x26,0x67,0x66,0x89,0x4f,0xfc + + /* %edi += entry_size, store as mbs_mmap_length */ + add %ecx, %edi movw %di, %fs:0x2c - /* %di = 4 + (entry_number * 24) */ - add $4, %di - jmp mmap_loop + + /* Continuation value 0 means last entry */ + test %ebx, %ebx + jnz mmap_loop mmap_done: real_to_prot: |