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To: Nate Lawson <nate@root.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 02 Jun 2004 09:36:20 PDT."
             <20040602093149.D35427@root.org> 
Date: Thu, 03 Jun 2004 00:39:44 +0200
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Subject: Re: cvs commit: src/sys/boot/i386/boot2 boot1.S 
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In message <20040602093149.D35427@root.org>, Nate Lawson writes:

>By removing the callw/retw and moving the jmp to the end, A20 enable can't
>be called as a subroutine from elsewhere.  Will it be needed elsewhere?

Not that I could find.

>>  /*
>>   * Enable A20 so we can access memory above 1 meg.
>> + * Use the zero-valued %cx as a timeout for embedded hardware which do not
>> + * have a keyboard controller.
>>   */
>>  seta20: 	cli				# Disable interrupts
>> -seta20.1:	inb $0x64,%al			# Get status
>
>Should be a "movw TIMEOUT, %cx" here.  (Or whatever the timeout constant
>is.)

Uhm, you are aware that space is very limited, right ?  Please see
the constant above for how we get the TIMEOUT value.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.