Slackware Console Resolution when Dual Booting with Another Distro's GRUB2?

Question

I am tweaking my new Linux Installs on a new home-built machine. I installed Linux Mint 14 first followed by Slackware 14 and Arch Linux on separate partitions. I don't think it matters, but the machine (AMD A10 CPU with an A75 chipset MSI motherboard) is UEFI (and secure boot) capable but I am running it in Legacy BIOS mode, since I have not wrapped my brain around this whole UEFI thing. The 3TB hard drive is however partitioned using a GUID partition scheme (without an EFI partiton), though none of the partitions is greater than 2 TB (the largest partition on that drive is 1 TB). I have already spent a couple of evenings tweaking the installs and would rather leave them as is.

After wrestling with it several times, I have managed to get os-prober and GRUB2 to recognize the existance of the Slackware and Arch Linux partitons and to boot them correctly. The auto-genetated /boot/grub/grub.cfg file is a fairly elaborate (and frightening) affair with elaborate shell scripting including if-else scripts etc. It is beyond my level of comfort with editing GRUB and LILO config files (I can handle manual editing of a simple LILO or Legacy GRUB script).

After this lengthy introduction my question is this: I intend to use Slackware and Arch mainly from the command line. The console font and resolution on my 24 inch screen is a low resolution chunky affair and I would prefer to adjust the console resolution. I know how to do it to some extent using LILO in Slackware (even then it is a little unpredictable) but am now relying on Linux Mint's GRUB2 as the boot loader for the 3 distros (will also add Scientific Linux later).

How do I adjust the console resolution for Slackware and Arch (preferably independently) within GRUB2 installed from within Linux Mint?

Answer 1

It depends on whether you want to use the VESA framebuffer or the "native" one (radeon/nvidia/intel/matrox/whatever). If you decide to use the "native" framebuffer it should automagically detect the resolution of your screen, assuming you are using EDID enabled hardware (given the hardware you are mentioning, chances are low, that it's not). You might need to tweak init scripts or rebuild the kernel to make sure the proper driver is loaded/present.

In the first case (vesafb) you need to to pass correct vga option to kernel on boot (e.g. vga=0x31a will give you 1280x1024x16M IIRC). To get a full list of available options use vga=ask, some are also mentioned in kernel sources /Documentation/fb.

As far as changing the kernel boot parameters is concerned, you'll want to edit the GRUB(2) configuration - have a look for example at Archlinux GRUB2 wiki on what and where to edit - the configuration in /boot/grub2 is generated from the one in /etc, usually at least on every kernel update.

That said, you might want give ELILO a try, especially is you are used to LILO, or let the kernel be booted directly by the UEFI bootloader.

Unless you have some special needs, using a single (custom built) kernel for all installed distributions doesn't have to be a bad idea (in that case using a bootloader will probably be easier, due to limitations of the direct UEFI loading mentioned in the link above).