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nagmat84
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Joined: 27 Mar 2007
Posts: 271
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 Posted: Tue Nov 19, 2024 9:50 pm Post subject: Which framebuffer options need to be selected for console? |
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Which framebuffer options do I need to select in my kernel configuration if I wish to have a text console at native panel resolution as a fallback even if X/Waxland fails for some reason?
I am using UEFI boot with EFI stub and Plymouth boot animation. Fox X/Wayland I am using the i915 DRM driver. However, if (for some reason) X/Waxland fails and I need to fall back to the text console, I still want a "proper" console not the 80 char, 25 line legacy thing. Until now I was under the impression that I have to select CONFIG_FB_SIMPLE in combination with CONFIG_SYSFB_SIMPLEFB for that, but I was recently told that I should disable it. All my kernel configurations essentially look like this | Code: | Device Drivers -->
Firmware Drivers -->
[*] Mark VGA/VBE/EFI FB as generic framebuffer (CONFIG_SYSFB_SIMPLEFB)
Graphics Support -->
<*> Direct Rendering Manager --> (CONFIG_DRM)
[*] Enable legacy fbdev support for your modesetting driver (CONFIG_DRM_FBDEV_EMULATION)
<*> Intel 8xx/9xx/G3x/G4x/HD Graphics (CONFIG_DRM_I915)
< > Simple framebuffer driver (CONFIG_DRM_SIMPLEDRM)
Frame buffer Devices -->
<*> Support for frame buffer device drivers --> (CONFIG_FB)
[ ] EFI-based Framebuffer Support (CONFIG_FB_EFI)
<*> Simple Framebuffer Support (CONFIG_FB_SIMPLE) |
After giving it some thought, I believe CONFIG_DRM_FBDEV_EMULATION is all I need for Plymouth and a text console, right? (Besides CONFIG_DRM_I915 of course, or any other graphic card (CONFIG_AMDGPU, CONFIG_NOUVEAU) I have).
Is it safe to deselect CONFIG_FB and CONFIG_FB_SIMPLE and CONFIG_SYSFB_SIMPLEFB? Will there be any regression? The kernel help text says to select it, if unsure. That is why I did it. |
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flexibeast
Guru
Joined: 04 Apr 2022
Posts: 455
Location: Naarm/Melbourne, Australia
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dmpogo
Advocate
Joined: 02 Sep 2004
Posts: 3427
Location: Canada
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| Posted: Wed Nov 20, 2024 5:08 am Post subject: |
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Good question, I tried to setup a framebuffer on three machines - 2 with nvidia cards and one intel GPU and cant'say got nice results. Intel still got stuck at 80x24,
on nvidia machine has a card which cannot support full native resolution of a monitor. Even post and BIOS screen looks flickerry. However once we get to X, X sets lower resolution all right and everything is dandy. I tried to teach framebuffer to set lower resolution for the screen, with no success. And only the second nvidia machine has higher resolution framebuffer on console, but it is quite slow. I need to find time and do a new attempt |
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irets
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Joined: 17 Dec 2019
Posts: 229
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| Posted: Wed Nov 20, 2024 11:47 am Post subject: |
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I'm not sure if this is of any help to you but I have these set.
| Code: | $ grep CONFIG_FB /usr/src/linux/.config | grep -v "^#"
CONFIG_FB=y
CONFIG_FB_VESA=y
CONFIG_FB_CORE=y
CONFIG_FB_NOTIFY=y
CONFIG_FB_CFB_FILLRECT=y
CONFIG_FB_CFB_COPYAREA=y
CONFIG_FB_CFB_IMAGEBLIT=y
CONFIG_FB_SYS_FILLRECT=y
CONFIG_FB_SYS_COPYAREA=y
CONFIG_FB_SYS_IMAGEBLIT=y
CONFIG_FB_SYS_FOPS=y
CONFIG_FB_DEFERRED_IO=y
CONFIG_FB_IOMEM_FOPS=y
CONFIG_FB_IOMEM_HELPERS=y
CONFIG_FB_SYSMEM_HELPERS=y
CONFIG_FB_SYSMEM_HELPERS_DEFERRED=y
CONFIG_FB_TILEBLITTING=y |
And then I use Grub to set the preferred console size.
| Code: | $ cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-6.6.58-wired-r1-x86_64 root=UUID=478832c6-257f-4147-8c79-01c22a1c5aef ro vga=0x317 fbcon=nodefer |
I've heard using vga=xyz is a deprecated approach but it works for me.
I also prefer a larger text size than some people. |
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pietinger
Moderator
Joined: 17 Oct 2006
Posts: 5120
Location: Bavaria
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| Posted: Wed Nov 20, 2024 5:58 pm Post subject: |
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| nagmat84 wrote: | Which framebuffer options do I need to select in my kernel configuration if I wish to have a text console at native panel resolution as a fallback even if X/Waxland fails for some reason?
I am using UEFI boot with EFI stub and Plymouth boot animation. Fox X/Wayland I am using the i915 DRM driver. However, if (for some reason) X/Waxland fails and I need to fall back to the text console, I still want a "proper" console not the 80 char, 25 line legacy thing. Until now I was under the impression that I have to select CONFIG_FB_SIMPLE in combination with CONFIG_SYSFB_SIMPLEFB for that, but I was recently told that I should disable it. All my kernel configurations essentially look like this | Code: | Device Drivers -->
Firmware Drivers -->
[*] Mark VGA/VBE/EFI FB as generic framebuffer (CONFIG_SYSFB_SIMPLEFB)
Graphics Support -->
<*> Direct Rendering Manager --> (CONFIG_DRM)
[*] Enable legacy fbdev support for your modesetting driver (CONFIG_DRM_FBDEV_EMULATION)
<*> Intel 8xx/9xx/G3x/G4x/HD Graphics (CONFIG_DRM_I915)
< > Simple framebuffer driver (CONFIG_DRM_SIMPLEDRM)
Frame buffer Devices -->
<*> Support for frame buffer device drivers --> (CONFIG_FB)
[ ] EFI-based Framebuffer Support (CONFIG_FB_EFI)
<*> Simple Framebuffer Support (CONFIG_FB_SIMPLE) |
After giving it some thought, I believe CONFIG_DRM_FBDEV_EMULATION is all I need for Plymouth and a text console, right? (Besides CONFIG_DRM_I915 of course, or any other graphic card (CONFIG_AMDGPU, CONFIG_NOUVEAU) I have).
Is it safe to deselect CONFIG_FB and CONFIG_FB_SIMPLE and CONFIG_SYSFB_SIMPLEFB? Will there be any regression? The kernel help text says to select it, if unsure. That is why I did it. |
We have 3 "simple"-options in the kernel ... two of them cause problems with some machines:
CONFIG_SYSFB_SIMPLEFB and CONFIG_DRM_SIMPLEDRM
Therefore I dont recommed them. (IF you do a configuration from scratch = with the default settings, THEN both are disabled; therefore both are not mentionend in my Wiki article for configuring the kernel).
The third one is usually not needed ... because you need only one of CONFIG_FB_EFI or CONFIG_FB_VESA. So, CONFIG_FB_SIMPLE is only in use if both of them do not work (you can use FB_SIMPLE as "fallback"). See also: https://wiki.gentoo.org/wiki/User:Pietinger/Experimental/Manual_Configuring_Current_Kernel#Framebuffer_Device_and_Console
If you want a different size you can set it also in the kernel configuration directly (I need it because I have a 4k monitor and the default font size is too small for me):
https://wiki.gentoo.org/wiki/User:Pietinger/Experimental/Manual_Configuring_Current_Kernel#Library_routines
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