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.)

11 files changed, 97 insertions, 84 deletions

diff --git a/NEWS b/NEWS
index 6810082f..8626a1d5 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,9 @@ Changes in 3.62:
 	  Linux kernel limit.
 	* vesamenu: support systems without linear framebuffer support
 	  (sigh, what is this, 1993?) and 15-bit RGB modes.
+	* Move the label storage (for the command-line interface) to
+	  high memory, removing the size limit and freeing up 64K of
+	  low memory.
 
 Changes in 3.61:
 	* EXTLINUX: fix crash when accessing an empty file.
diff --git a/com32.inc b/com32.inc
index 220c9d7b..ac513593 100644
--- a/com32.inc
+++ b/com32.inc
@@ -57,7 +57,6 @@ is_com32_image:
 		sub cx,si
 		fs rep movsb
 
-		call highmemsize	; We need the high memory size...
 		call comboot_setup_api	; Set up the COMBOOT-style API
 
 		mov edi,pm_entry	; Load address
@@ -115,9 +114,10 @@ com32_enter_pm:
 ;
 com32_call_start:
 		;
-		; Point the stack to the end of high memory
+		; Point the stack to the end of (permitted) high memory
 		;
-		mov esp,[word HighMemSize]
+		mov esp,[word HighMemRsvd]
+		xor sp,sp		; Align to a 64K boundary
 
 		;
 		; Set up the protmode IDT and the interrupt jump buffers
diff --git a/configinit.inc b/configinit.inc
index c6591b60..a5eaf1b3 100644
--- a/configinit.inc
+++ b/configinit.inc
@@ -19,9 +19,10 @@
 		section .text
 
 reset_config:
-		xor eax,eax
+		call highmemsize
 
 		; Initialize the .config section
+		xor eax,eax
 		mov si,section..config.start
 		mov di,section..config.vstart
 		mov cx,section..config.end.start
@@ -50,6 +51,9 @@ mkkeymap:	stosb
 		inc al
 		loop mkkeymap
 
+		mov eax,[HighMemSize]
+		mov [VKernelEnd],eax
+
 		ret
 
 		section .data
diff --git a/extlinux.asm b/extlinux.asm
index 232a58f3..8b2eff5b 100644
--- a/extlinux.asm
+++ b/extlinux.asm
@@ -56,7 +56,7 @@ SYMLINK_SECTORS	equ 2			; Max number of sectors in a symlink
 ; The following structure is used for "virtual kernels"; i.e. LILO-style
 ; option labels.  The options we permit here are `kernel' and `append
 ; Since there is no room in the bottom 64K for all of these, we
-; stick them at vk_seg:0000 and copy them down before we need them.
+; stick them in high memory and copy them down before we need them.
 ;
 		struc vkernel
 vk_vname:	resb FILENAME_MAX	; Virtual name **MUST BE FIRST!**
@@ -76,9 +76,8 @@ vk_end:		equ $			; Should be <= vk_size
 ;
 ; 0000h - main code/data segment (and BIOS segment)
 ;
-real_mode_seg	equ 4000h
-cache_seg	equ 3000h		; 64K area for metadata cache
-vk_seg          equ 2000h		; Virtual kernels
+real_mode_seg	equ 3000h
+cache_seg	equ 2000h		; 64K area for metadata cache
 xfer_buf_seg	equ 1000h		; Bounce buffer for I/O to high mem
 comboot_seg	equ real_mode_seg	; COMBOOT image loading zone
 
diff --git a/isolinux.asm b/isolinux.asm
index 81caf766..be8fd0f7 100644
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -50,7 +50,7 @@ SECTOR_SIZE	equ (1 << SECTOR_SHIFT)
 ; The following structure is used for "virtual kernels"; i.e. LILO-style
 ; option labels.  The options we permit here are `kernel' and `append
 ; Since there is no room in the bottom 64K for all of these, we
-; stick them at vk_seg:0000 and copy them down before we need them.
+; stick them in high memory and copy them down before we need them.
 ;
 		struc vkernel
 vk_vname:	resb FILENAME_MAX	; Virtual name **MUST BE FIRST!**
@@ -67,8 +67,7 @@ vk_end:		equ $			; Should be <= vk_size
 ; Segment assignments in the bottom 640K
 ; 0000h - main code/data segment (and BIOS segment)
 ;
-real_mode_seg	equ 3000h
-vk_seg          equ 2000h		; Virtual kernels
+real_mode_seg	equ 2000h
 xfer_buf_seg	equ 1000h		; Bounce buffer for I/O to high mem
 comboot_seg	equ real_mode_seg	; COMBOOT image loading zone
 
diff --git a/ldlinux.asm b/ldlinux.asm
index 0c5c94f8..0f063154 100644
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -58,7 +58,7 @@ SECTOR_SIZE	equ (1 << SECTOR_SHIFT)
 ; The following structure is used for "virtual kernels"; i.e. LILO-style
 ; option labels.  The options we permit here are `kernel' and `append
 ; Since there is no room in the bottom 64K for all of these, we
-; stick them at vk_seg:0000 and copy them down before we need them.
+; stick them in high memory and copy them down before we need them.
 ;
 		struc vkernel
 vk_vname:	resb FILENAME_MAX	; Virtual name **MUST BE FIRST!**
@@ -78,9 +78,8 @@ vk_end:		equ $			; Should be <= vk_size
 ;
 ; 0000h - main code/data segment (and BIOS segment)
 ;
-real_mode_seg	equ 4000h
-cache_seg	equ 3000h		; 64K area for metadata cache
-vk_seg          equ 2000h		; Virtual kernels
+real_mode_seg	equ 3000h
+cache_seg	equ 2000h		; 64K area for metadata cache
 xfer_buf_seg	equ 1000h		; Bounce buffer for I/O to high mem
 comboot_seg	equ real_mode_seg	; COMBOOT image loading zone
 
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
diff --git a/pxelinux.asm b/pxelinux.asm
index 7237fff4..8bb87c26 100644
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -101,7 +101,7 @@ TFTP_EOPTNEG	equ htons(8)		; Option negotiation failure
 ; The following structure is used for "virtual kernels"; i.e. LILO-style
 ; option labels.  The options we permit here are `kernel' and `append
 ; Since there is no room in the bottom 64K for all of these, we
-; stick them at vk_seg:0000 and copy them down before we need them.
+; stick them in high memory and copy them down before we need them.
 ;
 		struc vkernel
 vk_vname:	resb FILENAME_MAX	; Virtual name **MUST BE FIRST!**
@@ -119,9 +119,8 @@ vk_end:		equ $			; Should be <= vk_size
 ; Segment assignments in the bottom 640K
 ; 0000h - main code/data segment (and BIOS segment)
 ;
-real_mode_seg	equ 4000h
-pktbuf_seg	equ 3000h		; Packet buffers segments
-vk_seg          equ 2000h		; Virtual kernels
+real_mode_seg	equ 3000h
+pktbuf_seg	equ 2000h		; Packet buffers segments
 xfer_buf_seg	equ 1000h		; Bounce buffer for I/O to high mem
 comboot_seg	equ real_mode_seg	; COMBOOT image loading zone
 
diff --git a/rllpack.inc b/rllpack.inc
index 0714956a..e5d1d5e5 100644
--- a/rllpack.inc
+++ b/rllpack.inc
@@ -1,5 +1,4 @@
-; -*- fundamental -*-
-; -----------------------------------------------------------------------
+; -*- fundamental -*- ---------------------------------------------------
 ;
 ;   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
 ;
@@ -22,29 +21,37 @@
 ; 129-255	= (x-126) times subsequent byte
 ; 0		= end of data
 ;
+; These structures are stored *in reverse order* in high memory.
+; High memory pointers point to one byte beyond the end.
+;
 
 		section .text
 
 ;
 ; rllpack:
-;	Pack CX bytes from DS:SI into ES:DI
-;	Returns updated SI, DI and CX = number of bytes output
+;	Pack CX bytes from SI into EDI.
+;	Returns updated SI and EDI.
 ;
 rllpack:
-		push ax
-		push bx
+		push word .pmentry
+		call simple_pm_call
+		ret
+
+.pmentry:
 		push cx
-		push bp
-		push di
+		push ebx
+		push edx
 .startseq:
 		xor ax,ax		; Zero byte
-		xor bx,bx		; Run length zero
-		mov bp,di		; Pointer to header byte
-		stosb			; Store header byte (might be zero)
+		xor ebx,ebx		; Run length zero
+		dec edi
+		mov edx,edi		; Pointer to header byte
+		mov [edi],al
 		jcxz .done_null
 .stdbyte:
 		lodsb
-		stosb
+		dec edi
+		mov [edi],al
 		dec cx
 		cmp ah,al
 		je .same
@@ -53,7 +60,7 @@ rllpack:
 		xor bx,bx
 .plainbyte:
 		inc bx
-		inc byte [es:bp]
+		inc byte [edx]
 		jcxz .done
 		jns .stdbyte
 		jmp .startseq
@@ -61,18 +68,20 @@ rllpack:
 		cmp bl,2
 		jb .plainbyte
 		; 3 bytes or more in a row, time to convert sequence
-		sub byte [es:bp],bl
+		sub [edx],bl
 		jnz .normal
-		dec di			; We killed a whole stretch, remove start byte
+		inc edi			; We killed a whole stretch,
+					; drop start byte
 .normal:
 		inc bx
-		sub di,bx
-		mov bp,di
+		add edi,ebx
 		mov al,bl
 		add al,126
-		stosb
-		mov al,ah
-		stosb
+		dec edi
+		mov edx,edi
+		mov [edi],al
+		dec edi
+		mov [edi],ah
 .getrun:
 		jcxz .done
 		cmp bl,255-126
@@ -81,52 +90,57 @@ rllpack:
 		cmp al,ah
 		jne .nomatch
 		inc bx
-		inc byte [es:bp]
+		inc byte [edx]
 		dec cx
 		jmp .getrun
 .nomatch:
 		dec si
 		jmp .startseq
 .done:
-		xor al,al
-		stosb
+		dec edi
+		mov [edi],cl		; CX = 0 here
 .done_null:
-		pop dx
-		sub dx,di
-		neg dx
-		pop bp
+		pop edx
+		pop ebx
 		pop cx
-		pop bx
-		pop ax
 		ret
 ;
 ; rllunpack:
-;	Unpack bytes from DS:SI into ES:DI
-;	On return SI, DI are updated and CX contains number of bytes output
+;	Unpack bytes from ESI into DI
+;	On return ESI, DI are updated and CX contains number of bytes output.
 ;
 rllunpack:
-		push ax
+		push word .pmentry
+		call simple_pm_call
+		ret
+
+.pmentry:
 		push di
 		xor cx,cx
 .header:
-		lodsb
+		dec esi
+		mov al,[esi]
 		and al,al
 		jz .done
 		cmp al,129
 		jae .isrun
 		; Not a run
 		mov cl,al
-		rep movsb
+.copy:
+		dec esi
+		mov al,[esi]
+		stosb
+		loop .copy
 		jmp .header
 .isrun:
 		sub al,126
 		mov cl,al
-		lodsb
+		dec esi
+		mov al,[esi]
 		rep stosb
 		jmp .header
 .done:
 		pop cx
 		sub cx,di
 		neg cx
-		pop ax
 		ret
diff --git a/runkernel.inc b/runkernel.inc
index 39d8e908..98d826f0 100644
--- a/runkernel.inc
+++ b/runkernel.inc
@@ -97,10 +97,14 @@ kernel_sane:	push ax
 ; Save the cluster pointer for later...
 ;
 		push si
+
 ;
-; Get the BIOS' idea of what the size of high memory is.
+; Initialize our end of memory pointer
 ;
-		call highmemsize
+		mov eax,[HighMemRsvd]
+		xor ax,ax			; Align to a 64K boundary
+		mov [MyHighMemSize],eax
+
 ;
 ; Construct the command line (append options have already been copied)
 ;
@@ -195,7 +199,7 @@ is_mem_cmd:
 %if HIGHMEM_SLOP != 0
 		sub ebx,HIGHMEM_SLOP
 %endif
-		mov [cs:HighMemSize],ebx
+		mov [cs:MyHighMemSize],ebx
 		jmp short skip_this_opt
 cmdline_end:
                 push cs                         ; Restore standard DS
@@ -256,7 +260,7 @@ read_kernel:
                 mov si,dotdot_msg		; Print dots
                 call cwritestr
 
-                mov eax,[HighMemSize]
+                mov eax,[MyHighMemSize]
 		sub eax,100000h			; Load address
 		cmp eax,[KernelSize]
 		jb no_high_mem		; Not enough high memory
@@ -592,7 +596,7 @@ loadinitrd:
 		mov es,ax
 
 		push ecx			; Bytes to load
-		mov edx,[HighMemSize]		; End of memory
+		mov edx,[MyHighMemSize]		; End of memory
 		dec edx
 		mov eax,[RamdiskMax]		; Highest address allowed by kernel
 		cmp edx,eax
@@ -670,6 +674,7 @@ boot_image_len  equ $-boot_image
 
 		section .bss
 		alignb 4
+MyHighMemSize	resd 1			; Possibly adjusted highmem size
 RamdiskMax	resd 1			; Highest address for ramdisk
 KernelSize	resd 1			; Size of kernel in bytes
 KernelSects	resd 1			; Size of kernel in sectors
diff --git a/ui.inc b/ui.inc
index 7e5ac112..69ba7dc6 100644
--- a/ui.inc
+++ b/ui.inc
@@ -297,19 +297,14 @@ clin_opt_ok:
 ; Now check if it is a "virtual kernel"
 ;
 vk_check:
-		xor si,si			; Beginning of vk_seg
+		mov esi,[HighMemSize]		; Start from top of memory
 .scan:
-		cmp si,[VKernelBytes]
-		jae .not_vk
-
-		push ds
-		push word vk_seg
-		pop ds
+		cmp esi,[VKernelEnd]
+		jbe .not_vk
 
 		mov di,VKernelBuf
 		call rllunpack
-		pop ds
-		; SI updated on return
+		; ESI updated on return
 
 		sub di,cx			; Return to beginning of buf
 		push si