Date: Tue, 24 Jan 2006 14:27:48 -0800 (PST)
From: "Randy.Dunlap" <rdunlap@xenotime.net>
To: Ed Sweetman <safemode@comcast.net>
cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org,
       akpm@osdl.org
Subject: Re: 2.6.16-rc1-mm2 pata driver confusion
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On Tue, 24 Jan 2006, Ed Sweetman wrote:

> Alan Cox wrote:
>
> >On Maw, 2006-01-24 at 01:43 -0500, Ed Sweetman wrote:
> >
> >
> >>problem.  The problem is that there appears to be two nvidia/amd ata
> >>drivers and I'm unsure which I should try using, if i compile both in,
> >>which get loaded first (i assume scsi is second to ide) and if i want my
> >>pata disks loaded under the new libata drivers, will my cdrom work under
> >>them too, or do i still need some sort of regular ide drivers loaded
> >>just for cdrom (to use native ata mode for recording access).
> >>
> >>
> >
> >The goal of the drivers/scsi/pata_* drivers is to replace drivers/ide in
> >its entirity with code using the newer and cleaner libata logic. There
> >is still much to do but my SIL680, SiS, Intel MPIIX, AMD and VIA boxes
> >are using libata and the additional patch patches still queued
> >
> >
>
> >>1.  Atapi is most definitely not supported by libata, right now.
> >>
> >>
> >
> >It works in the -mm tree.
> >
> >
> Intriguing, when I had no ide chipset compiled in kernel, only libata
> drivers, I got no mention at all about my dvd writer.  I even had the
> scsi cd driver installed and generic devices, still nothing seemed to
> initialize the dvd drive.  It detected the second pata bus but no
> devices attached to it.
>
> this is using the kernel mentioned in the subject header.
> 2.6.16-rc1-mm2.  using the amd/nvidia drivers for pata and sata.
>
> Is there anything i can do to give more info to the list to figure out
> why my atapi writer is being ignored by pata even when there are no ide
> drivers loaded?

Currently you need to use libata.atapi_enabled=1
(assuming that libata is in the kernel image, not a loadable module).

I just built/tested this also, working for me as well.
(hard drives, not ATAPI)

> >>4.  moving to pata libata drivers _will_ change the enumeration of your
> >>sata devices, it seems that pata is initialized first, so when setting
> >>up your fstab entries and grub, you'll have to take into account how
> >>many pata devices you have and offset your current sata device names by
> >>that amount.
> >>
> >>
> >
> >Or use labels. As you move into the world of hot pluggable hardware it
> >becomes more and more impractical to guarantee drive ordering by name.
> >
> >You can mix and match the drivers providing you don't try and load both
> >libata and old ide drives for the same chip. Even then it should fail
> >correctly with one of them reporting resources unavailable.
> >
> >In fact I do this all the time when debugging so I've got a stable disk
> >for debug work and a devel disk.
> >
> >Alan
> >
> >
>
> I'm not familiar with labeling ...will have to look into it, since
> borking a kernel after changing the drivers can result in a non-bootable
> system depending on how the partitions are setup across the devices.
> (since you'd have to change them in fstab and such before a reboot).  A
> way around that would be very useful.

-- 
~Randy
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