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author | H. Peter Anvin <hpa@zytor.com> | 2008-07-03 15:29:57 -0700 |
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committer | H. Peter Anvin <hpa@zytor.com> | 2008-07-03 15:29:57 -0700 |
commit | fb75c40b2d119afcef002cb66d359536ad576ff6 (patch) | |
tree | d8307a50aa4b292c068c6e9301f745a97971fd6c | |
parent | 8e5db045c60ce25a9eb65a1803d47be4002a3e17 (diff) | |
download | syslinux-fb75c40b2d119afcef002cb66d359536ad576ff6.tar.gz |
doc/memdisk.txt: document INT 1Eh fields
Document the fields to recover the original INT 1Eh vector.
-rw-r--r-- | doc/memdisk.txt | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/doc/memdisk.txt b/doc/memdisk.txt index 304de52b..34a85406 100644 --- a/doc/memdisk.txt +++ b/doc/memdisk.txt @@ -161,7 +161,7 @@ http://www.ctyme.com/rbrown.htm, for a detailed description. The MEMDISK info structure currently contains: - [ES:DI] word Total size of structure (currently 28 bytes) + [ES:DI] word Total size of structure (currently 30 bytes) [ES:DI+2] byte MEMDISK minor version [ES:DI+3] byte MEMDISK major version [ES:DI+4] dword Pointer to MEMDISK data in high memory @@ -171,9 +171,15 @@ The MEMDISK info structure currently contains: [ES:DI+20] 16:16 Old INT 15h pointer [ES:DI+24] word Amount of DOS memory before MEMDISK loaded [ES:DI+26] byte Boot loader ID + [ES:DI+27] byte Currently unused + [ES:DI+28] word If nonzero, offset (vs ES) to installed DPT + This pointer+16 contains the original INT 1Eh -MEMDISK 3.00 and higher has the size of this structure as 27; earlier -versions had size 26 and did not include the boot loader ID. +Sizes of this structure: + +3.71+ 30 bytes Added DPT pointer +3.00-3.70 27 bytes Added boot loader ID +pre-3.00 26 bytes In addition, the following fields are available at [ES:0]: @@ -185,8 +191,9 @@ this API can be used. The following code can be used to "disable" MEMDISK. Note that it does not free the handler in DOS memory, and that running this from -DOS will probably crash your machine (DOS doesn't like drives -suddenly disappearing from underneath): +DOS will probably crash your machine (DOS doesn't like drives suddenly +disappearing from underneath.) This is also not necessarily the best +method for this. mov eax, 454D0800h mov ecx, 444D0000h |