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Re: Matrox G550 - MGA X server fails




It does seem to be related to video drivers more generally. Outside X the console driver from grub fails to reduce the size of text.

Since I am using grub version 2, it will take a lot of research to find out what the scripts are doing. There is no simple VGA= parameter to change. I have set the X server to setuid and am going to swap the video card back in and try again later.

On 22 Mar 2017 8:12 pm, "Sven Joachim" <svenjoac@xxxxxx> wrote:
On 2017-03-22 10:25 +0000, Oliver Elphick wrote:

> I am unable to start X using a Matrox Millennium G550 PCIe card.
>
> This is what I think is the relevant part of the log for the session:
>
> #011compiled for 1.19.2, module version = 0.1.0
> #011ABI class: X.Org Video Driver, version 23.0
> (--) MGA(0): Chipset: "mgag550"
> xf86TokenToOptinfo: table is NULL
> xf86TokenToOptinfo: table is NULL
> (==) MGA(0): Using HW cursor
> (--) MGA(0): Linear framebuffer at 0xF0000000
> (--) MGA(0): MMIO registers at 0xF7020000
> (--) MGA(0): Pseudo-DMA transfer window at 0xF6800000
> (EE) MGA(0): Unable to map Framebuffer F0000000 2000000.  Permission
> denied (13)
> (II) MGA(0): Creating default Display subsection in Screen section
> #011"Default Screen Section" for depth/fbbpp 24/32
> (==) MGA(0): Depth 24, (--) framebuffer bpp 32
> (==) MGA(0): RGB weight 888
> (==) MGA(0): Using AGP 1x mode
> (==) MGA(0): Using XAA acceleration
> (WW) MGA(0): Could not retrieve video BIOS!
> (EE) MGA(0): Unable to detect video RAM.
> (II) UnloadModule: "mga"
>
> The full log is attached.
>
> Can anyone indicate what the problem is, please?

Probably that the X server is no longer running with root rights, and
it has to do that if there is no kernel driver for the graphics card.
See /usr/share/doc/xserver-xorg-core/NEWS.Debian.gz:

,----
| xorg-server (2:1.17.3-1) unstable; urgency=medium
|
|   The Xorg server is no longer setuid root by default.  This change reduces the
|   risk of privilege escalation due to X server bugs, but has some side effects:
|
|   * it relies on logind and libpam-systemd
|   * it relies on a kernel video driver (so the userspace component doesn't
|     touch the hardware directly)
|   * it needs X to run on the virtual console (VT) it was started from
|   * it changes the location for storing the Xorg log from /var/log/ to
|     ~/.local/share/xorg/
|
|   On systems where those are not available, the new xserver-xorg-legacy package
|   is needed to allow X to run with elevated privileges.  See the
|   Xwrapper.config(5) manual page for configuration details.
|
|  -- Julien Cristau <jcristau@xxxxxxxxxx>  Tue, 27 Oct 2015 22:54:11 +0000
`----

In short, you need to install xserver-xorg-legacy.

Cheers,
       Sven