linux-kernel - Re: kexec and framebuffer

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Date:	Fri, 21 Jul 2006 07:28:51 +0800
From:	"Antonino A. Daplas" <adaplas@...il.com>
To:	Kalev Lember <kalev@...rtlink.ee>
CC:	Gerd Hoffmann <kraxel@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: kexec and framebuffer

Kalev Lember wrote:
> Gerd Hoffmann wrote:
>>> I am wondering what would be the preferred method to extract screen_info
>>> from running kernel. Should this be made available from sysfs or maybe a
>>> new system call be created?
>>>     
>> Simply ask /dev/fb0?
>> Patch for kexec tools attached.
>>   
> Thank you, this was really helpful.
>> +	if (0 != strcmp(fix.id, "vesafb"))
>> +		goto out;
> I think this check should be removed so that other framebuffer drivers
> besides vesafb would also work.

I think having the check is correct, only vesafb relies totally on
screen_info. If you remove the check, you can get the wrong information
from other framebuffer drivers.

> +	/* fixme: better get size from /proc/iomem */
> +	real_mode->lfb_size       = (fix.smem_len + 65535) / 65536;
> +	real_mode->pages          = (fix.smem_len + 4095) / 4096;

Note that fix.smem_len is the size of the remapped memory which can be
smaller than the actual framebuffer length. But there's a fixme comment
there so you probably know about this.

> Additionally the fix.id is "VESA VGA",
> not "vesafb".

Yes.

Tony
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