Remove last users of getcbuf; reclaim the address space

Remove the last few uses of getcbuf (to extend trackbuf for shuffle
descriptors, and for temp storage during pxelinux config file search.)
As a result, change the way RBFG_brainfuck is handled in pxelinux (at
some point it's probably not worth maintaining anymore, as RBFG is no
longer widely used); add a .bss2 section for the region between the
RBFG zone and the stack.

6 files changed, 23 insertions, 20 deletions

diff --git a/comboot.inc b/comboot.inc
index 9d9ca247..3a9b4332 100644
--- a/comboot.inc
+++ b/comboot.inc
@@ -604,7 +604,7 @@ comapi_dnsresolv equ comapi_err
 ; INT 22h AX=0011h	Maximum number of shuffle descriptors
 ;
 comapi_maxshuffle:
-		mov P_CX,(2*trackbufsize)/12
+		mov P_CX,trackbufsize/12
 		ret
 
 ;
diff --git a/extlinux.asm b/extlinux.asm
index 9459f568..aa785892 100644
--- a/extlinux.asm
+++ b/extlinux.asm
@@ -109,8 +109,7 @@ file_mode	resw 1
 		section .earlybss
 trackbufsize	equ 8192
 trackbuf	resb trackbufsize	; Track buffer goes here
-getcbuf		resb trackbufsize
-		; ends at 4800h
+		; ends at 2800h
 
 		section .bss1
 SuperBlock	resb 1024		; ext2 superblock
diff --git a/isolinux.asm b/isolinux.asm
index e0c41ea4..e485532d 100644
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -102,8 +102,7 @@ dir_clust	resd 1			; Length in clusters
 		section .earlybss
 trackbufsize	equ 8192
 trackbuf	resb trackbufsize	; Track buffer goes here
-getcbuf		resb trackbufsize
-;		ends at 4800h
+;		ends at 2800h
 
 		; Some of these are touched before the whole image
 		; is loaded.  DO NOT move this to .uibss.
diff --git a/layout.inc b/layout.inc
index 4ee78746..ba6b231b 100644
--- a/layout.inc
+++ b/layout.inc
@@ -52,6 +52,23 @@ STACK_START	equ TEXT_START-STACK_SIZE
 		; but are in order to offload .bss
 		section .bss1		nobits valign=16 vfollows=.config.end
 
+		; Warning here: RBFG build 22 randomly overwrites
+		; memory location [0x5680,0x576c), possibly more.  It
+		; seems that it gets confused and screws up the
+		; pointer to its own internal packet buffer and starts
+		; writing a received ARP packet into low memory.
+%if IS_PXELINUX
+		section .rbfg		nobits start=0x5680
+RBFG_brainfuck:	resb 2048		; Bigger than an Ethernet packet...
+%endif
+
+		; For section following .rbfg
+%if IS_PXELINUX
+		section .bss2		nobits valign=16 vfollows=.rbfg
+%else
+		section .bss2		nobits valign=16 vfollows=.bss1
+%endif
+
 		section .text		start=TEXT_START
 		; NASM BUG: .data always follows .text; can't override
 		section .data		align=16 ; follows=.text
diff --git a/ldlinux.asm b/ldlinux.asm
index 468e2b8e..217fb15d 100644
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -108,8 +108,7 @@ file_left	resd 1			; Number of sectors left
 		section .earlybss
 trackbufsize	equ 8192
 trackbuf	resb trackbufsize	; Track buffer goes here
-getcbuf		resb trackbufsize
-		; ends at 4800h
+		; ends at 2800h
 
 		section .bss
 		alignb 8
diff --git a/pxelinux.asm b/pxelinux.asm
index 02f38c02..f9e911cf 100644
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -186,12 +186,7 @@ tftp_pktbuf	resw 1			; Packet buffer offset
 		section .earlybss
 trackbufsize	equ 8192
 trackbuf	resb trackbufsize	; Track buffer goes here
-getcbuf		resb trackbufsize
-		; ends at 4800h
-
-		; Put some large buffers here, before RBFG_brainfuck,
-		; where we can still carefully control the address
-		; assignments...
+		; ends at 2800h
 
 		alignb open_file_t_size
 Files		resb MAX_OPEN*open_file_t_size
@@ -204,12 +199,6 @@ IPOption	resb 80			; ip= option buffer
 InitStack	resd 1			; Pointer to reset stack (SS:SP)
 PXEStack	resd 1			; Saved stack during PXE call
 
-; Warning here: RBFG build 22 randomly overwrites memory location
-; [0x5680,0x576c), possibly more.  It seems that it gets confused and
-; screws up the pointer to its own internal packet buffer and starts
-; writing a received ARP packet into low memory.
-RBFG_brainfuck	resb 0E00h
-
 		section .bss
 		alignb 4
 RebootTime	resd 1			; Reboot timeout, if set by option
@@ -818,7 +807,7 @@ config_scan:
 		call writestr
 		call crlf
 		mov si,di
-		mov di,getcbuf
+		mov di,KernelName	;  Borrow this buffer for mangled name
 		call mangle_name
 		call open
 		popa