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edid & bochs

Posted: Thu Feb 19, 2026 6:26 am
by CodePoet2005
Hi fellow devs,

Im writing a bootloader from scratch and im now getting the edid info to pick the best video mode.
In qemu i can specify a preferred resolution using the following command line option:

Code: Select all

-device VGA,edid=on,xres=1920,yres=1080
My bootloader successfully picks this mode.

In bochs however i haven't found an similar option. The edid does exists (can get it from the bios) but it contains a non existent resolution: 1920 x 1200. No vbe mode matches this.


Also is it even worth it selecting the preferred resolution?
Any decent monitor and graphics card supports ancient resolutions.

Does anyone have any ideas why the bochs edid contains a false preferred mode (or how i can change it)?

Cheers,
CodePoet2005

Re: edid & bochs

Posted: Thu Feb 19, 2026 8:37 am
by gmoney
In your bochsrc do you see a line that looks like this? ( vga: extension=vbe, edid=on )

Re: edid & bochs

Posted: Thu Feb 19, 2026 9:29 am
by CodePoet2005
Hi,
gmoney wrote: Thu Feb 19, 2026 8:37 am In your bochsrc do you see a line that looks like this? ( vga: extension=vbe, edid=on )
Thank you so much, adding

Code: Select all

vga: extension=vbe
fixed the strange edid. The edid now contains a nice 1920x1080 preferred resolution.

Cheers,
CodePoet2005

Re: edid & bochs

Posted: Fri Feb 20, 2026 9:04 am
by gmoney
No problem, and don't have too much fun coding 🤣