Re: kexec and framebuffer

From: Antonino A. Daplas
Date: Thu Jul 20 2006 - 19:27:21 EST

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(, "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 is "VESA VGA",
> not "vesafb".


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at