2.2.16 SMP: mtrr errors

Quoted 7 lines · Petr Vandrovec

Quoted 2 lines

kernel: mtrr: base(0xd4000000) is not aligned on a size(0x1800000) boundary last message repeated 2 times

For some strange reason X thinks that you have 24MB of memory on the G450. You can either create 32MB write-combining region at 0xd4000000, or teach X that your device occupies 32MB and not 24 (you should do it anyway, region size can be only power of two)...

Petr, the Matrox card splits the memory between the two video screens when running in a multi-head configuration and "pretends" that it is two distinct cards. Thus, a 32 mb card will register an mtrr for 24mb and for 8mb seperately when in this mode.

That's wrong. They must first register MTRR and then split it to 24+8, as they cannot register 24MB range. They can split it 16+16, or (16+8)+8, but at cost of 1 (or 2) additional MTRR entries - and there is very limited number of possible MTRRs.

Matroxfb also splits Matrox memory in 24:8, but it registers only one region in mtrr. Of course, in X, as mtrr registration is done by map videomemory, you must tell this function to not register mtrr...

Best regards,
Petr Vandrovec [email protected]