diff options
Diffstat (limited to 'core/pxelinux.asm')
| -rw-r--r-- | core/pxelinux.asm | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/core/pxelinux.asm b/core/pxelinux.asm index ff0f36c8..929ab673 100644 --- a/core/pxelinux.asm +++ b/core/pxelinux.asm @@ -255,12 +255,21 @@ _start1: 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 @@ -2258,11 +2267,11 @@ do_reset_pxe: 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. |