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authorH. Peter Anvin <hpa@linux.intel.com>2010-06-21 15:12:48 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-06-21 15:16:33 -0700
commit2f712545dd82f5906ec930b643d44e8b12295682 (patch)
tree039959551677ed36c25da6740d54bdc03c7846ac
parent079300e7afce204191279ea56ba9cb7592ec28c8 (diff)
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comboot: allow the read disk API call to specify a 64-bit LBA
We already had two MBZ fields reserved, so use one of them to expand into a 64-bit LBA. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
-rw-r--r--core/comboot.inc4
-rw-r--r--doc/comboot.txt4
2 files changed, 4 insertions, 4 deletions
diff --git a/core/comboot.inc b/core/comboot.inc
index 0c9956a0..91cc15ae 100644
--- a/core/comboot.inc
+++ b/core/comboot.inc
@@ -837,10 +837,10 @@ comapi_userfont:
;
%if IS_SYSLINUX || IS_ISOLINUX || IS_EXTLINUX
comapi_readdisk:
- mov esi,P_ESI ; Enforce ESI == EDI == 0, these
- or esi,P_EDI ; are reserved for future expansion
+ cmp P_EDI,0 ; Reserved for future expansion
jnz .err
mov eax,P_EDX
+ mov edx,P_ESI
mov es,P_ES
mov bx,P_BX
mov bp,P_CX ; WE CANNOT use P_* after touching bp!
diff --git a/doc/comboot.txt b/doc/comboot.txt
index 036bd784..9e9f99a0 100644
--- a/doc/comboot.txt
+++ b/doc/comboot.txt
@@ -832,8 +832,8 @@ AX=0018h [3.30] Query custom font
AX=0019h [3.50] Read disk [SYSLINUX, ISOLINUX, EXTLINUX]
Input: AX 0019h
- EDX Sector number
- ESI Reserved - MUST BE ZERO
+ EDX Sector number (LSW)
+ ESI Sector number (MSW) [4.00]
EDI Reserved - MUST BE ZERO
CX Sector count
ES:BX Buffer address