Re: How to enable DMA at boot time
On Sun, Dec 01, 2002 at 05:27:58PM -0800, Vineet Kumar wrote:
> * Clive Standbridge (nobody@i.love.spam) [021127 09:46]:
> > On Wed 27 Nov 2002 04:13:08 +0000(+0000), Pigeon wrote:
> >
> > 4:13am! Is Pigeon really an owl?
> >
> > > Try ide0=ata66 (for UDMA66; change as appropriate)
> > >
> > > Works for me.
> >
> > I tried both ide0=ata66 and ide0=ata100 but neither worked. The
> > parameters went onto the kernel command line reported by dmesg and
> > kern.log (and some other logs), but had no other obvious effect.
>
> Documentation/ide.txt (from the Linux kernel tree) shows the ide options
> available at boot, and includes this line:
>
> "idex=dma" : automatically configure/use DMA if possible.
>
> I don't see any mention of ata or udma options there, but you could try
> and see if "ide0=dma" does anything for you.
I think he already has...
Doing a quick grep " ata" * in the abovementioned Documentation directory
reveals the following in Configure.help:
AMD Viper ATA-66 Override support (WIP)
CONFIG_AMD74XX_OVERRIDE
This option auto-forces the ata66 flag.
This effect can be also invoked by calling "idex=ata66"
^^^^^^^^^^^^
This is not where I originally got it from; alas I can't remember
where that was. Might have been the LOADLIN docs. There was a good
paragraph or so on it. But I'm not gonna grep every file on my system
(well, not yet...)
I think the difference is that dma just tells it to use any old form
of dma, whereas ata66 tells it to use that speed even if it hasn't
detected it from the BIOS or wherever, which it doesn't on my system,
so I use this setting and get a "WARNING! ATA66/100 forced bit set"
message during bootup - the point of the warning being that this
option would make it try to use 66MHz even if the hardware really
didn't support it.
Pigeon
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