- This topic has 0 replies, 1 voice, and was last updated Nov 25-8:15 am by anticapitalista.
November 25, 2019 at 8:15 am #29859Forum Adminanticapitalista
This is a direct copy from the post by hazel (many thanks) over at linuxquestions.org forums.
Some old video drivers do not work easily with modern kernels. The openchrome driver, used for Via Chrome graphics is one that does not. The problem is the kernel flag CONFIG_IO_STRICT_DEVMEM which, for security reasons, prevents userspace programs from accessing hardware registers. This prevents these drivers from mapping the framebuffer unless special steps are taken.
The installation disc may fail to start X unless a safe mode boot is selected. In the installed system, the vesa driver is used instead of the chip-specific driver, but it gives very poor results with tearing and ghost cursors, especially when there is a load on the cpu.
1. Use the kernel command line parameter “iomem=relaxed”. This allows proper framebuffer mapping. For a one-off boot in this mode, simply press “e” when you see the GRUB menu, to enter edit mode. Scroll down to the kernel command line and add the required parameter.
2. To make the change permanent, you need to edit (as root) the /etc/default/grub file. There is a line in the file for the kernel command line. Simply add the “iomem=relaxed” parameter to this line. Then run update-grub. Every subsequent update of GRUB will include the new parameter.
3. This change alone makes the vesa driver work much better. The image is sharper, there is no tearing and no ghosts. However there may still be problems with the video mode, causing a mismatch between the picture size and the screen. This disappears when you use the card-specific driver. But because this driver was not in use during installation, you must either edit it into /etc/X11/xorg.conf in place of the vesa driver or add an extra configuration file in /etc/X11/xorg.conf.d, for example:
Section "Device" Identifier "Videocard0" Driver "Openchrome" VendorName "Via" EndSection
Philosophers have interpreted the world in many ways; the point is to change it.
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