Date: Fri, 31 Dec 1999 09:32:27 -0800 From: R Joseph Wright <rjoseph@nwlink.com> To: "Norman C. Rice" <nrice@emu.sourcee.com>, freebsd-questions@FreeBSD.org Subject: Re: some performance issues Message-ID: <386CE8AB.29A140B5@nwlink.com> References: <386C023E.680FC31@inna.net> <386C0676.F39EC477@3-cities.com> <386C2354.ABD1ED54@nwlink.com> <386C3173.1D695393@3-cities.com> <386C543D.6E59C9DF@nwlink.com> <19991231104441.C2609@emu.sourcee.com>
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"Norman C. Rice" wrote:
>
> On Thu, Dec 30, 1999 at 10:59:09PM -0800, R Joseph Wright wrote:
> >
> > >
> > > The 0x2000 allows IDE DMA transfers and that could be part of your
> > > problem. Some drives like that setting and some systems don't. It is
> > > something that you can try by seting it at boot time. If it works,
> > > then you build it into your kernel. My drives are all 0xa0ffa0ff.
> > > 8+2=a.
> >
> > Where did the 8+2 come from? This is really confusing to me. Do you
> > mean that you get both 2000 and 80ff at the same time by using a?
> > Thanks in advance, Joseph <):-{>
>
> Binary Decimal Hexadecimal
> 0000 0 0
> 0001 1 1
> 0010 2 2
> 0011 3 3
> 0100 4 4
> 0101 5 5
> 0110 6 6
> 0111 7 7
> 1000 8 8
> 1001 9 9
> 1010 10 A
> 1011 11 B
> 1100 12 C
> 1101 13 D
> 1110 14 E
> 1111 15 F
>
> 8 + 2 = Decimal 10 or Hexadecimal A
>
> In binary,
>
> 1000 (8)
> +0010 (2)
> ----
> 1010 (decimal 10, hexadecimal A)
>
> Using the 'a' instead of the '8' enables both of the following
> features rather than just the 32 bit transfer capability.
>
> 0x8000 Test and use the 32bit transfer capability of the drive.
>
> 0x2000 Probe for and use the bus-mastering DMA capabilities of
> modern PCI chipsets.
That's making some sense. Now, what does the ff in 0xa0ff stand for?
Happy Millenium :-]
Joseph
> --
> Regards,
> Norman C. Rice, Jr.
--
You will do foolish things,
but do them with enthusiasm. Colette.
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