diff options
Diffstat (limited to 'mbr/gptmbr.S')
| -rw-r--r-- | mbr/gptmbr.S | 44 |
1 files changed, 24 insertions, 20 deletions
diff --git a/mbr/gptmbr.S b/mbr/gptmbr.S index 8d42e8b8..20741acb 100644 --- a/mbr/gptmbr.S +++ b/mbr/gptmbr.S @@ -40,8 +40,6 @@ phdr = stack /* Above the stack, overwritten by bootsect */ /* To handle > 32K we need to play segment tricks... */ psec = _phdr + 512 -/* BootGUID */ -bootguid = _start + 0x1a8 /* Where we put DS:SI */ dssi_out = _start + 0x1be @@ -148,24 +146,31 @@ get_ptab: loopw get_ptab /* Find the boot partition */ - popw %si /* Partition table in memory */ + xorw %si,%si /* Nothing found yet */ + popw %di /* Partition table in memory */ popw %cx /* NumberOfPartitionEntries */ popw %ax /* SizeOfPartitionEntry */ + find_part: - pushw %cx - pushw %si - addw $16,%si - movw $bootguid,%di - movw $8,%cx - repe; cmpsw - popw %si - popw %cx - je found_part - addw %ax,%si + testb $0x04,48(%di) + jz not_this + andw %si,%si + jnz found_multiple + movw %di,%si +not_this: + addw %ax,%di loopw find_part + andw %si,%si + jnz found_part + +missing_os: call error - .ascii "Boot partition not found\r\n" + .ascii "Missing OS\r\n" + +found_multiple: + call error + .ascii "Multiple active partitions\r\n" found_part: xchgw %ax,%cx /* Set up %cx for rep movsb further down */ @@ -191,6 +196,9 @@ found_part: call inc64 call saturate_stosl /* Partition length */ + movzwl %cx,%eax /* Length of GPT entry */ + stosl + rep; movsb /* GPT entry follows MBR entry */ popw %si @@ -200,8 +208,8 @@ found_part: * is phdr == 0x7c00 == the address of the boot sector. */ boot: - movl (32+16)(%si),%eax - movl (36+16)(%si),%edx + movl (32+20)(%si),%eax + movl (36+20)(%si),%edx popw %bx call read_sector cmpw $0xaa55, -2(%bx) @@ -214,10 +222,6 @@ boot: cli jmpw *%sp /* %sp == bootsec */ -missing_os: - call error - .ascii "OS not bootable\r\n" - saturate_stosl: pushl %eax andl %edx,%edx |