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From: Romit Dasgupta <>
Subject: Trivial Change (E820map) : arch/i386/boot/setup.S
Date: Thu, 17 Jul 2003 01:33:19 +0800	[thread overview]
Message-ID: <> (raw)

      After reading the e820 method from Ralf Brown's interrupt list(
it seems that the es register wont get thrashed. So there is no need to 
repatedly execute (for getting each map entry) the following two lines 
inside jmpe820: of seutp.S and thus can be moved out as below.  Is there 
any reason to do it inside?

        pushw   %ds
        popw    %es

        movl    $0x0000e820, %eax               # e820, upper word zeroed
        movl    $SMAP, %edx                     # ascii 'SMAP'
        movl    $20, %ecx                       # size of the e820rec
#       pushw   %ds                             # data record.
#       popw    %es


===== setup.S 1.22 vs edited =====
 >       pushw   %ds
 >       popw    %es
<       pushw   %ds                             # data record.
<       popw    %es
 > #       pushw %ds                             # data record.
 > #       popw  %es

Tested in my i386 machine and here is the relevant portion of dmesg 
after boot.

> Linux version 2.6.0-test1 (root@feynman) (gcc version 3.2 20020903 
> (Red Hat Linux 8.0 3.2-7)) #14 Thu Jul 17 01:05:15 SGT 2003
> Video mode to be used for restore is f00
> BIOS-provided physical RAM map:
>  BIOS-e820: 0000000000000000 - 000000000009f800 (usable)
>  BIOS-e820: 000000000009f800 - 00000000000a0000 (reserved)
>  BIOS-e820: 00000000000e0000 - 0000000000100000 (reserved)
>  BIOS-e820: 0000000000100000 - 0000000017ff0000 (usable)
>  BIOS-e820: 0000000017ff0000 - 0000000017ffec00 (ACPI data)
>  BIOS-e820: 0000000017ffec00 - 0000000018000000 (ACPI NVS)
>  BIOS-e820: 00000000fff80000 - 0000000100000000 (reserved)
> 0MB HIGHMEM available.
> 383MB LOWMEM available.
> On node 0 totalpages: 98288


             reply	other threads:[~2003-07-16 17:21 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-07-16 17:33 Romit Dasgupta [this message]
2003-07-16 18:18 ` Trivial Change (E820map) : arch/i386/boot/setup.S Alan Cox

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