[ECOS] i386 Memory Size Problem
Tue Nov 25 16:30:00 GMT 2003
I found some sample code that makes the calls that I need.
Are there any examples of storing to the c/C++ variables that would help me to do the port?
From: email@example.com [mailto:firstname.lastname@example.org]On Behalf Of
Sent: Tuesday, November 25, 2003 2:58 AM
To: LEMAY,KEVIN (A-Roseville,ex1)
Subject: Re: [ECOS] i386 Memory Size Problem
> 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
More information about the Ecos-discuss