Re: IDE-flash device and hard disk on same controller

From: Andre Hedrick (
Date: Thu Aug 22 2002 - 22:14:59 EST

On 22 Aug 2002, Eric W. Biederman wrote:

> Jeff Garzik <> writes:
> > Eric W. Biederman wrote:
> > > I don't see any checking for the ATA bsy flag before you start sending
> > > commands. I have seen the current IDE code fail too many times if I
> > > boot to fast, because of a lack of this one simple test. So I don't
> > > see how this could be considered a proper probe.
> >
> >
> > There is no ATA bsy flag check at only one point, and that is before EXECUTE
> > DEVICE DIAGNOSTIC is issued. The idea with this command is that it pretty much
> > stomps up and down the ATA bus, trouncing ongoing activity in the process.
> The problem is that immediately after bootup ATA devices do not respond until
> their media has spun up. Which is both required by the spec, and observed in
> practice. Which is likely a problem if this code is run a few seconds after
> bootup. Which makes it quite possible the drive will ignore the EXECUTE DEVICE
> DIAGNOSTICS and your error code won't be valid when the bsy flag
> clears. I don't know how serious that would be.

We did POST already.

> I can test and find out but I would rather confine my testing to
> commands that look like they will stay within the realms of
> predictable behavior.
> And yes with LinuxBIOS I can reliably boot up fast enough to make this
> problem show up in practice.
> Eric

Andre Hedrick
LAD Storage Consulting Group

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