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+;; -----------------------------------------------------------------------
+;;
+;; Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
+;;
+;; 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,
+;; Boston MA 02111-1307, USA; either version 2 of the License, or
+;; (at your option) any later version; incorporated herein by reference.
+;;
+;; -----------------------------------------------------------------------
+
+;;
+;; cpuinit.inc
+;;
+;; CPU-dependent initialization and related checks.
+;;
+
+check_escapes:
+ mov ah,02h ; Check keyboard flags
+ int 16h
+ mov [KbdFlags],al ; Save for boot prompt check
+ test al,04h ; Ctrl->skip 386 check
+ jnz skip_checks
+
+;
+; Now check that there is sufficient low (DOS) memory
+;
+; NOTE: Linux doesn't use all of real_mode_seg, but we use the same
+; segment for COMBOOT images, which can use all 64K
+;
+dosram_k equ (real_mode_seg+0x1000) >> 6 ; Minimum DOS memory (K)
+ int 12h
+ cmp ax,dosram_k
+ jae enough_ram
+ mov si,err_noram
+ call writestr
+ jmp kaboom
+enough_ram:
+skip_checks:
+
+;
+; Initialize the bcopy32 code in low memory
+;
+ mov si,__bcopy32_lma
+ mov di,__bcopy32_start
+ mov cx,__bcopy32_dwords
+ rep movsd
+
+;
+; Check if we're 386 (as opposed to 486+); if so we need to blank out
+; the WBINVD instruction
+;
+; We check for 486 by setting EFLAGS.AC
+;
+%if DO_WBINVD
+ pushfd ; Save the good flags
+ pushfd
+ pop eax
+ mov ebx,eax
+ xor eax,(1 << 18) ; AC bit
+ push eax
+ popfd
+ pushfd
+ pop eax
+ popfd ; Restore the original flags
+ xor eax,ebx
+ jnz is_486
+;
+; 386 - Looks like we better blot out the WBINVD instruction
+;
+ mov byte [try_wbinvd],0c3h ; Near RET
+is_486:
+%endif ; DO_WBINVD
+
+ section .data
+err_noram db 'It appears your computer has less than '
+ asciidec dosram_k
+ db 'K of low ("DOS")'
+ db CR, LF
+ db 'RAM. Linux needs at least this amount to boot. If you get'
+ db CR, LF
+ db 'this message in error, hold down the Ctrl key while'
+ db CR, LF
+ db 'booting, and I will take your word for it.', CR, LF, 0
+ section .text