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Setting up MTRR for X11 or mga_vid:
===================================
1. find the base address
~~~~~~~~~~~~~~~~~~~~~~~~
You have 3 ways to find it:
- from X11 startup messages, for example:
(--) SVGA: PCI: Matrox MGA G400 AGP rev 4, Memory @ 0xd8000000, 0xd4000000
(--) SVGA: Linear framebuffer at 0xD8000000
- from /proc/pci (use lspci -v command):
01:00.0 VGA compatible controller: Matrox Graphics, Inc.: Unknown device 0525
Memory at d8000000 (32-bit, prefetchable)
- from mga_vid kernel driver messages (use dmesg):
mga_mem_base = d8000000
2. find memory size
~~~~~~~~~~~~~~~~~~~
This is very easy, just convert video ram size to hexadecimal, or
use this table:
1 MB 0x100000
2 MB 0x200000
4 MB 0x400000
8 MB 0x800000
16 MB 0x1000000
32 MB 0x2000000
3. setting up mtrr
~~~~~~~~~~~~~~~~~~
You know base address and memory size, let's setup mtrr registers!
For example, for the matrox card above (base=0xd8000000) with 32MB
ram (size=0x2000000) just execute:
echo "base=0xd8000000 size=0x2000000 type=write-combining" >| /proc/mtrr
- Older K6-2's [around 266Mhz, stepping 0] doesn't support MTRR.
- K6-2 with 'stepping 12' (do a cat /proc/cpuinfo) supports MTRR.
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