[LinuxBIOS] ram_resource question

Corey Osgood corey.osgood at gmail.com
Sat Oct 13 05:18:04 CEST 2007


oops, meant to cc the list, apparently can't from my cell :(

joe at smittys.pointclark.net wrote:
> Quoting Corey Osgood <corey.osgood at gmail.com>:
>
>> It's board specific, if you saw that in i810, it's for onboard vga.
>> -Corey
>>
>> On 10/12/07, joe at smittys.pointclark.net <joe at smittys.pointclark.net>
>> wrote:
>>> Hello,
>>>
>>> Can someone tell me what this memory region is reserved for?
>>> It is 1MB to The Top Of Low Memory - 1MB right?
>>> Is the last 1MB chipset specific or needed for the LinuxBIOS bounce
>>> buffer?
>>>
>>> ram_resource(dev, idx++, 1024, tolmk - 1024;
>>>
>>> Oh, this is from northbridge.c if you were wondering. I need to know
>>> this, because Intel IGD reserves memory from the The Top Of Physical
>>> Memory down.
>>> If this is the case should I subtract the IGD memory before or after
>>> this function is called.
>>>
>>> Example 1:
>>> tolmk -= IGD_MEMORYK
>>> ram_resource(dev, idx++, 1024, tolmk - 1024;
>>>
>>> OR
>>>
>>> Example 2:
>>> ram_resource(dev, idx++, 1024, (tolmk - IGD_MEMORYK) - 1024);
>>> ram_resource(dev, idx++, (tolmk - IGD_MEMORYK) - 1024, tolmk -
>>> IGD_MEMORYK);
>>>
>>>
>>> Thanks - Joe
>>>
>>> -- 
>>> linuxbios mailing list
>>> linuxbios at linuxbios.org
>>> http://www.linuxbios.org/mailman/listinfo/linuxbios
>>>
>>
> Hmm, I saw where you set the
>
> /* Enable 1MB framebuffer. */
> //pci_write_config8(ctrl->d0, SMRAM, 0xC0);
>
> In raminit.c but no mention of this in northbridge.c.

I have no idea why I left the 1MB subtraction in there, probably because
at the time I was planning on getting back to it and just haven't yet.

> But if that is what that last 1MB is for I can just do a:
>
> ram_resource(dev, idx++, 1024, tolmk - IGD_MEMORYK;
>
> Right?? But, if I do this then is the IGD_MEMORYK going to be
> initialized?

Yes. But is there any way to use CONFIG_VIDEO_MB instead of a new config
option? Perhaps have 0 or 2 = 512k?

> From the datasheet:
> The pre-allocated memory allows sizes of 512 KB, 1 MB, or 8 MB. The
> system BIOS must properly initialize these regions.

This is exactly what it's talking about ;)

-Corey




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