path: root/doc
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authorH. Peter Anvin <hpa@zytor.com>2010-06-27 12:02:48 -0700
committerH. Peter Anvin <hpa@zytor.com>2010-06-27 12:02:48 -0700
commitb775b0040fe57ef71ec9cd98f9c124a3d116269b (patch)
treeec85cf4b93d4d6ad4e5aa0eeeff0c8db14149a6c /doc
parent7ccf85b2a873bba3f363ad2df05457dd160c3f6d (diff)
Export the 64-bit partition offset and use it in chain.c
When used with the "fs" option to chain.c32, we need to know our own filesystem offset. That means knowing if we used the MBR vs GPT partition information, as well as if we ended up using the passed-in information or not. Resolve this by providing an explicit pointer to the current partition offset. Eventually this should be replaced by some kind of statfs() call. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'doc')
1 files changed, 5 insertions, 4 deletions
diff --git a/doc/comboot.txt b/doc/comboot.txt
index 9e9f99a0..4b4b8803 100644
--- a/doc/comboot.txt
+++ b/doc/comboot.txt
@@ -426,8 +426,12 @@ AX=000Ah [2.00] Get Derivative-Specific Information
Output: AL 31h (SYSLINUX), 34h (EXTLINUX)
DL drive number
CL sector size as a power of 2 (9 = 512 bytes) [3.35]
+ CH mode [3.73]
+ 1 = CBIOS mode
+ 2 = EBIOS mode
ES:BX pointer to partition table entry (if DL >= 80h)
FS:SI pointer to initial ES:DI value [3.53]
+ GS:DI pointer to partition offset (QWORD) [4.00]
Note: This function was broken in EXTLINUX 3.00-3.02.
@@ -501,6 +505,7 @@ AX=000Ah [2.00] Get Derivative-Specific Information
2 = Hybrid (hard disk), EBIOS mode
ES:BX pointer to El Torito spec packet
FS:SI pointer to initial ES:DI value [3.53]
+ GS:DI pointer to partition offset (QWORD) [4.00]
Note: Some very broken El Torito implementations do
not provide the spec packet information. If so, ES:BX
@@ -508,10 +513,6 @@ AX=000Ah [2.00] Get Derivative-Specific Information
AX=4B01h to obtain the spec packet directly from the
BIOS if necessary.
- This call gives information specific to a particular Syslinux
- derivative. The value returned in AL is the same as is
- returned in DL by INT 22h AX=0001h.
AX=000Bh [2.00] Get Serial Console Configuration