Put virtual kernels (CLI labels) in high memorysyslinux-3.62-pre7

Support putting virtual kernels in high memory instead of using a
dedicated segment for it.  This both reduces the low memory footprint
by 64K, and allows for functionally unlimited labels (tested with over
a hundred thousand.)

1 files changed, 11 insertions, 15 deletions

diff --git a/parseconfig.inc b/parseconfig.inc
index 739a884b..90c1f3c9 100644
--- a/parseconfig.inc
+++ b/parseconfig.inc
@@ -399,23 +399,12 @@ commit_vk:
 		xor ax,ax
 		rep stosb
 
-		; Pack temporarily into trackbuf
+		; Pack into high memory
 		mov si,VKernelBuf
-		mov di,trackbuf
+		mov edi,[VKernelEnd]
 		mov cx,vk_size
 		call rllpack
-		; Now DX = number of bytes
-		mov di,[VKernelBytes]
-		mov cx,dx
-		add dx,di
-		jc .overflow			; If > 1 segment
-		mov [VKernelBytes],dx
-		mov si,trackbuf
-		push es
-		push word vk_seg
-		pop es
-		rep movsb
-		pop es
+		mov [VKernelEnd],edi
 		ret
 .overflow:
 		mov si,vk_overflow_msg
@@ -426,6 +415,14 @@ commit_vk:
 vk_overflow_msg	db 'Out of memory parsing config file', CR, LF, 0
 SerialNotice	db 1			; Only print this once
 
+		section .bss
+		alignb 4
+VKernelEnd	resd 1			; Lowest high memory address used
+
+		; This symbol should be used by loaders to indicate
+		; the highest address *they* are allowed to use.
+HighMemRsvd	equ VKernelEnd
+					; by vkernels
 		section .config
 		align 4, db 0
 KbdTimeout      dd 0                    ; Keyboard timeout (if any)
@@ -440,7 +437,6 @@ AllowImplicit   dw 1                    ; Allow implicit kernels
 AllowOptions	dw 1			; User-specified options allowed
 IncludeLevel	dw 1			; Nesting level
 SerialPort	dw 0			; Serial port base (or 0 for no serial port)
-VKernelBytes	dw 0			; Number of bytes used by vkernels
 VKernel		db 0			; Have we seen any "label" statements?
 
 %if IS_PXELINUX