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Re: Bus error in macscsi_pread

On 11/21/06, Brad Boyer <flar@allandria.com> wrote:
On Tue, Nov 21, 2006 at 11:41:31PM -0500, De Served wrote:
> Trying to get Sarge installed on an LCIII.   I'm using the following
> command line arguments:   root=/dev/ram ramdisk_size=13000
> Everything seems to work quite well until I get the bus error.   This is
> the output:
> SCSI device sda: 333936 512-byte hdwr sectors (171 MB)
> Bus error in macscsi_pread
> sd 0:0:0:0: switching to slow handshake
> and the boot process freezes at this point.  Any ideas?

I didn't realize this bug hadn't been fixed yet. The pseudo-DMA
routines in the mac_scsi driver got broken at some point, which
means that you have to disable that feature to get working drive
access. It also means your disk performance will go down to some
very painfully slow speeds. This came up recently on the mailing
list and some suggestions were made. The command line addition I
suggested was this one:


This will tell the driver not to attempt pseudo-DMA at all.

My main test box is a IIfx, which has this feature disabled
in the code because the scsi chip is just a little different
and only works with the slow code path.

        Brad Boyer

i only had this problem on my lcIII when i was working with the 2.6.17 kernels.

What is this a 170mb disc, besides that is tiny
it is probably way too old, may as well go back to kernel 1.0. that thing needs
pulled (IMHO).

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