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; -----------------------------------------------------------------------
;
; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
; Copyright 2009 Intel Corporation; author: H. Peter Anvin
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
; Bostom MA 02111-1307, USA; either version 2 of the License, or
; (at your option) any later version; incorporated herein by reference.
;
; -----------------------------------------------------------------------
;
; layout.inc
;
; Memory layout of segments
;
; Default to 16-bit code
bits 16
; Memory below 0800h is reserved for the BIOS and the MBR.
BSS_START equ 0800h
; Text starts at the load address of 07C00h.
TEXT_START equ 7C00h
; The secondary BSS section, above the text; we really wish we could
; just make it follow .bcopy32 or hang off the end,
; but it doesn't seem to work that way.
LATEBSS_START equ 0B800h
%ifdef MAP
[map all MAP]
%endif
;
; The various sections and their relationship
;
; Use .earlybss for things that MUST be in low memory.
section .earlybss nobits start=BSS_START
section .config write progbits align=4
section .replacestub exec write progbits align=16
; Use .bss for things that doesn't have to be in low memory;
; with .bss1 and .bss2 to offload. .earlybss should be used
; for things that absolutely have to be below 0x7c00.
section .bss write nobits align=16
%if 0 ; IS_PXELINUX
; 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.
section .rbfg write nobits
RBFG_brainfuck: resb 2048 ; Bigger than an Ethernet packet...
%endif
section .bss2 write nobits align=16
section .text exec write progbits align=16
section .bcopyxx exec write progbits align=16
section .data write progbits align=16
section .adv write nobits align=512
; .uibss contains bss data which is guaranteed to be
; safe to clobber during the loading of the image. This
; is because while loading the primary image we will clobber
; the spillover from the last fractional sector load.
section .uibss write nobits align=16
; Normal bss...
section .bss1 write nobits align=16
; Symbols from linker script
%macro SECINFO 1
extern __%1_start, __%1_lma, __%1_end
extern __%1_len, __%1_dwords
%endmacro
SECINFO config
SECINFO replacestub
global _start
section .text
;
; Segment assignments in the bottom 640K
; Keep the low-memory footprint as small as possible... overrun is a hard
; failure!
;
; 0000h - main code/data segment (and BIOS segment)
aux_seg equ 1000h ; Currently holds the font buffer
;
; Contents of aux_seg
;
struc aux
.fontbuf resb 8192
endstruc
;
; Bounce buffer for I/O to high mem
; Note: we keep all the segments page-aligned, even if that probably
; is somewhat excessive. Sector alignment is obligatory, however.
;
xfer_buf_seg equ aux_seg + (((aux_size + 4095) & ~4095) >> 4)
%if IS_ISOLINUX
; ISOLINUX doesn't have a block cache yet
real_mode_seg equ xfer_buf_seg + 1000h
%else
cache_seg equ xfer_buf_seg + 1000h ; 64K area for metadata cache
real_mode_seg equ xfer_buf_seg + 2000h
pktbuf_seg equ cache_seg ; PXELINUX packet buffers
%endif
comboot_seg equ real_mode_seg ; COMBOOT image loading zone
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