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MTRR mystery (Announce)

posted by RayeR Homepage, CZ, 30.01.2012, 15:03
(edited by RayeR on 31.01.2012, 02:39)

> @RayeR
> >
> RE: enabling LFB writecombining on i5/ i7, your post on the other site is
> exactly what I was referring to. I referenced in my search in finding a way
> to enable LFB WC on i7 in DOS... i thought you may have found a solution by
> now. Sad that so few DOS users are left. This MPLAYER build is exactly the
> type of program which eill utilize ALL the CPU power in the latest
> SandyBridge processors...

Damn! Yesterday I tried my VESATEST under pure DOS again and suddenly I found that WC for LFB stopped working! First I though this was caused by last changes to my MTRR code but when I tried older versions that was surely working but now not. Now I'm getting only abou 160MB/s instead of 2700MB/s. Under Win98 it still works. I tried CMOS reset, BIOS reflash and still don't works! Getting headache of it... I was trying to remember what else I changed on my HW and few months ago I was upgrading RAM from 2GB to 4GB. When I come at home I'll try pull one DIMM out.
Maybe there rise a problem when LFB on VGA overlaps system memory and some additional process is needed. My i5 machine at work has 8GB in 2 modules so I cannot test it only with 2GB... But there must be a way how Win98 did it. Or maybe I'm completly wrong and it's caused by something else...

> Except for pthreads, which I do not even know if
> it is possible to utilize the extra CPU cores with DOS.
This would require to write a low-level APIC code that starts other CPU cores. Firts it's needed to acquire APIC IDs of all cores and then send them some enable signal. They start to execute prepared code from given address.

---
DOS gives me freedom to unlimited HW access.

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