mov ds,ax
mov es,ax
+%if 0 ; debugging code only... not intended for production use
; Clobber the stack segment, to test for specific pathologies
mov di,STACK_BASE
mov cx,STACK_LEN >> 1
mov ax,0xf4f4
rep stosw
+ ; Clobber the tail of the 64K segment, too
+ extern __bss1_end
+ mov di,__bss1_end
+ sub cx,di ; CX = 0 previously
+ shr cx,1
+ rep stosw
+%endif
+
; That is all pushed onto the PXE stack. Save the pointer
; to it and switch to an internal stack.
mov [InitStack],sp
TRACER 'F'
;
-; Look to see if we are on an EFI CSM system. Some EFI
-; CSM systems put the BEV stack in low memory, which means
-; a return to the PXE stack will crash the system. However,
-; INT 18h works reliably, so in that case hack the stack and
-; point the "return address" to an INT 18h instruction.
+; Look to see if we are on an EFI CSM system. Some EFI CSM systems
+; (AMI CSM) put the BEV stack in low memory (just below 64K), which
+; means a return to the PXE stack will crash the system. However, INT
+; 18h works reliably, so in that case hack the stack and point the
+; "return address" to an INT 18h instruction.
;
; Hack the stack instead of the much simpler "just invoke INT 18h
; if we want to reset", so that chainloading other NBPs will work.