Add a bootstrap chainloading API, and include a sample program for it.syslinux-2.08-pre5

1 files changed, 26 insertions, 1 deletions

diff --git a/comboot.doc b/comboot.doc
index 5d1a9547..768bf3c3 100644
--- a/comboot.doc
+++ b/comboot.doc
@@ -439,7 +439,7 @@ AX=000Ch	Perform final cleanup
 	MAKE SURE TO DISABLE INTERRUPTS, AND INSTALL NEW GDT AND IDTS
 	BEFORE OVERWRITING THESE MEMORY AREAS.
 
-	The permissible values for DX are as follows:
+	The permissible values for DX is an OR of these values:
 
 	SYSLINUX:	0000h	Normal cleanup
 
@@ -450,3 +450,28 @@ AX=000Ch	Perform final cleanup
 
 	All other values are undefined, and may have different
 	meanings in future versions of SYSLINUX.
+
+
+AX=000Dh	Cleanup and replace bootstrap code
+	Input:	AX	000Ch
+		DX	derivative-specific flags (see previous function)
+		EDI	bootstrap code (linear address, can be in high memory)
+		ECX	bootstrap code length in bytes (max 
+		EBX(!)	initial value of EDX after bootstrap
+		ESI	initial value of ESI after bootstrap
+		DS	initial value of DS after bootstrap
+	Output:	None
+
+	This routine performs final cleanup, then takes a piece of
+	code, copies it over the primary bootstrap at address 7C00h,
+	and jumps to it.  This can be used to chainload boot sectors,
+	MBRs, bootstraps, etc.
+
+	Normal boot sectors expect DL to contain the drive number,
+	and, for hard drives (DL >= 80h) DS:SI to contain a pointer to
+	the 16-byte partition table entry.  The memory between
+	600h-7FFh is available to put the partition table entry in.
+
+	For PXELINUX, if the PXE stack is not unloaded, all registers
+	(except DS, ESI and EDX) and the stack will be set up as they
+	were set up by the PXE ROM.