DOS ain't dead - more insight into BIOS MTRRs

more insight into BIOS MTRRs (Users)

posted by Ninho , 20.03.2011, 19:30

>> I had not had an incentive to look into this before, now digging a little
>> further, (plain DOS) : VESA BIOS reports the LFB at C0000000h (3 Giga), and
>> that is correct. But at the same time for some unfathomable reason
>> AMI/SiS BIOS erroneously has pointed the appropriate MTRR (MSR 20E/20F) to
>> phys address D0000000h instead of C0000000. "Plug and play" they say, let
>> me laugh :=)

> That's the plug and pray - the right meaning ;)

I always thought the right interpretation was pay and pray ;-)

...However, I gave the whole story a second look & changed my opinion, it's
no BIOS bug; rather the region, starting at D0000000, set to write-combining is the "AGP
aperture", not the LFB - the latter is left for an OS to set presumably.

Looking from Windows now, neither Win 98 nor 2k set an MTRR over the frame
buffer. I guess for such purpose they are using the PAT instead.

---
Ninho

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Complete thread:

PDF readers for DOS - travolter, 17.02.2011, 10:52 (Users)
- PDF readers for DOS - DOS386, 17.02.2011, 11:12
  - PDF readers for DOS - Laaca, 17.02.2011, 13:58
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        Tested PDFTK,,, *and* MUPDF with HX - rr, 18.02.2011, 20:59
        Tested PDFTK,,, *and* MUPDF with HX - RayeR, 19.02.2011, 01:05
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        MUPDF/DGJPP test release! - RayeR, 19.02.2011, 18:26
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        MUPDF/DGJPP test release! - Khusraw, 20.02.2011, 14:05
        MUPDF/DGJPP test release! - RayeR, 20.02.2011, 14:12
        MUPDF/DGJPP test release! - travolter, 20.02.2011, 14:52
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        MUPDF/DGJPP test release! - travolter, 20.02.2011, 18:15
        MUPDF/DGJPP test release! - FFK, 21.02.2011, 01:37
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        MUPDF/DGJPP test release! - Japheth, 21.02.2011, 08:41
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        MUPDF/DGJPP test release! - Laaca, 20.02.2011, 22:35
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        MUPDF/DGJPP test release! - travolter, 21.02.2011, 15:00
        MUPDF/DGJPP test release! - RayeR, 21.02.2011, 16:34
        MUPDF/DGJPP test release! - travolter, 21.02.2011, 19:50
        MUPDF/DGJPP test release! - RayeR, 22.02.2011, 01:50
        MUPDF/DGJPP test release! - travolter, 22.02.2011, 11:12
        MUPDF/DGJPP test release! - RayeR, 22.02.2011, 13:09
        MUPDF/DGJPP test release! - georgpotthast, 22.02.2011, 13:35
        MUPDF/DGJPP test release! - RayeR, 22.02.2011, 17:15
        MUPDF/DGJPP test release! - georgpotthast, 22.02.2011, 18:28
        MUPDF/DGJPP test release! - RayeR, 23.02.2011, 04:35
        MUPDF/DGJPP test release! - Zyzzle, 23.02.2011, 10:59
        MUPDF/DGJPP test release! - travolter, 22.02.2011, 17:18
        MUPDF/DGJPP test release! - RayeR, 22.02.2011, 17:26
        MUPDF/DGJPP test release! - Ninho, 22.02.2011, 21:05
        MUPDF/DGJPP test release! - RayeR, 23.02.2011, 00:27
        MUPDF/DGJPP test release! - Ninho, 23.02.2011, 11:43
        MUPDF/DGJPP test release! - RayeR, 23.02.2011, 13:17
        MUPDF/DGJPP test release! - Ninho, 23.02.2011, 17:19
        MUPDF/DGJPP test release! - RayeR, 23.02.2011, 19:33
        MUPDF/DGJPP test release! - Ninho, 23.02.2011, 19:50
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        MUPDF/DGJPP test release! - Ninho, 25.02.2011, 11:31
        MUPDF/DGJPP test release! - RayeR, 25.02.2011, 13:05
        MUPDF/DGJPP test release! - Ninho, 25.02.2011, 13:40
        MTRRLFBE -Good news ! - Ninho, 25.02.2011, 20:37
        MTRRLFBE -Good news ! - RayeR, 26.02.2011, 01:02
        more insight into BIOS MTRRs - Ninho, 20.03.2011, 19:30
        more insight into BIOS MTRRs - RayeR, 23.03.2011, 20:18
        more insight into BIOS MTRRs - Laaca, 23.03.2011, 23:25
        more insight into BIOS MTRRs - RayeR, 24.03.2011, 16:20
        more insight into BIOS MTRRs - Ninho, 24.03.2011, 16:56
        more insight into BIOS MTRRs - RayeR, 25.03.2011, 00:38
        more insight into BIOS MTRRs - Ninho, 26.03.2011, 11:41
        more insight into BIOS MTRRs - Laaca, 29.03.2011, 18:12
        more insight into BIOS MTRRs - RayeR, 29.03.2011, 22:03
        MUPDF/DGJPP test release! - Japheth, 23.02.2011, 18:14
        MUPDF/DGJPP test release! - RayeR, 23.02.2011, 19:36
        MUPDF/DGJPP test release! - Ninho, 25.02.2011, 15:30
        MUPDF/DGJPP test release | missing PDFDRAW.EXE | source cod - DOS386, 23.02.2011, 06:56
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        MUPDF/DGJPP test release | missing PDFDRAW.EXE | source cod - jassenna, 19.07.2011, 06:20
        MUPDF/DGJPP test release | missing PDFDRAW.EXE | source cod - jassenna, 20.08.2011, 06:24
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  - PDF readers for DOS - travolter, 18.02.2011, 12:24
- PDF readers for DOS - ron, 17.02.2011, 22:13
  - PDF readers for DOS - DOS386, 18.02.2011, 04:10
    - PDF readers for DOS - ron, 18.02.2011, 06:04
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