From: Nick Garnett <nickg@ecoscentric.com>
To: kevin_lemay@agilent.com
Cc: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] i386 Memory Size Problem
Date: Tue, 25 Nov 2003 10:57:00 -0000 [thread overview]
Message-ID: <m37k1oemvw.fsf@miso.calivar.com> (raw)
In-Reply-To: <1BEBA5E8600DD4119A50009027AF54A010FAE47E@axcs04.cos.agilent.com>
kevin_lemay@agilent.com writes:
> There appears to be an issue with the pcmb_misc.c file where it determines to actual amount of extended memory available.
>
> It is reading bytes 0x17 and 0x18 from the CMOS which limits the RAM size to 64MB.
>
> I was trying to find the proper way to find out the memory size, and found the following on the web.
>
> Use BIOS calls:
> INT 15h AX=E820h (32-bit CPU only). If this fails...
> ...use INT 15h AX=E801h. If this fails...
> ...use INT 15h AH=88h.
> Read the extended memory size from CMOS only if all of the BIOS calls listed above fail.
>
> How do I do this with eCos?
>
> I have a large application that I am porting that allocates lots of ram. I need more than 64MB.
>
You would need to put this code into the real mode startup code in
pcmb.inc or platform.inc. There's already calls to INT 15h AX=0x88 and
INT 12h there which just push the results, but then does nothing with
them -- I think this must be obsolete code. So the right thing to do is
probably to pull the pushed values after the switch to protected mode
and store them in cyg_hal_pcmb_memsize_base and
cyg_hal_pcmb_memsize_extended. Then just disable the options that
control the code in hal_pcmb_init().
--
Nick Garnett eCos Kernel Architect
http://www.ecoscentric.com The eCos and RedBoot experts
--
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss
next prev parent reply other threads:[~2003-11-25 10:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-24 22:53 kevin_lemay
2003-11-25 10:57 ` Nick Garnett [this message]
2003-11-25 16:30 kevin_lemay
2003-11-25 17:29 ` Nick Garnett
2003-11-25 22:24 kevin_lemay
2003-11-26 11:45 ` Nick Garnett
2003-12-02 20:13 kevin_lemay
2003-12-03 10:29 ` Nick Garnett
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