UEFI 800x600 display issue

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rbdavis
Posts: 15
Joined: 2007/07/31 23:49:00

UEFI 800x600 display issue

Post by rbdavis » 2020/02/12 20:58:00

Hi all,

I just installed a dual-boot Win10/CentOS7 (UEFI boot) system and am having a strange display resolution issue with Centos7. If I make CentOS7 the default boot target in the system's firmware boot priority config, when it comes up I get the expected 1280x1024 display resolution. However, if I make Windows the default boot but then manually intervene at powerup via the interactive UEFI boot menu and select CentOS to boot instead of Windows, I get 800x600 resolution. Although the system also offers legacy BIOS boot I seem to be stuck with UEFI as neither my Windows nor CentOS USB installer sticks will boot under BIOS for reasons completely unknown (although they will boot on another older legacy BIOS system!).

The system is a short 1U rack mount server with a single quad core Celeron J1900. lspci says my graphics is this:

00:02.0 VGA compatible controller [0300]: Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display [8086:0f31] (rev 0e)

When I boot as the UEFI default boot target /var/log/messages says:

efifb: framebuffer at 0xc0000000, mapped to 0xffffb4f641000000, using 5120k, total 5120k
efifb: mode is 1280x1024x32, linelength=5120, pages=1

When I manually boot via the UEFI powerup-time interactive boot menu, on the other hand, I get this:

efifb: framebuffer at 0xc0000000, mapped to 0xffffb83981000000, using 1876k, total 1875k
efifb: mode is 800x600x32, linelength=3200, pages=1


The two corresponding Xorg logfiles mirror this difference, i.e., they are essentially identical except that one thinks it's got a bigger frame buffer than the other.

So, something about the manual UEFI boot menu startup is making CentOS think it only has a 2MB frame buffer instead of a 5MB frame buffer. Can anyone tell me why this is happening and how I can fix it? I need to make Windows the default boot so I would really like to solve this.

Thanks!

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