Re: ibook system bus speed
* Lee Braiden <jel@tundra.ath.cx> [2005:03:10 16:18 +0000]:
> On Thursday 10 March 2005 12:43, Christophe Branchereau wrote:
> > ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
> >
> > A quick look on google told me that the system bus speed of this model is
> > 66MHz, as http://www.apple-history.com specifies.
> >
> > Isn't it degrading disk performances a lot?
> > As the dma mode that was set to 16 Bits by default, for example.
>
> Hmm.. interesting. I've noticed that message on my x86 machine, but I never
> spotted it on my iBook. Turns out I have it too. I would have expected the
> powermac controller to recognise the ppc laptop models (at least) and to know
> what they can handle. Guess not :)
>
> Here's what the kernel driver says on it (leaving out the x86-specific stuff):
>
> "idebus=xx" : inform IDE driver of VESA/PCI bus speed in MHz, where "xx" is
> between 20 and 66 inclusive, used when tuning chipset PIO modes. If in
> doubt, use idebus=33 for PCI. Bigger values are safer than smaller ones.
>
> Problem is, it says nothing about what actually happens with different
> values :(
>
> Worth noting here that you should probably be aiming for DMA rather than PIO,
> if your iBook can do DMA IDE transfers.
>
> --
> Lee.
That's interresting, thanks for the infos. If it's used only for PIO
modes, I don't need it at all since I use udma2.
My real problem is I replaced the original 6Gb IBM disk of the ibook
with a 20Gb Toshiba. Everything went fine until I fill up more than 6Gb
on the disk, then it begins to makes strange noises (tarataratara clac
clac to be precise) and the speed
decreases incredibly. I *know* the disk is OK, because I plugged it in
an x86 machine and everything is fine.
That made me think there must be a problem with the
IDE controller, that's why I thought of the bus speed value.
--
Christophe
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