On Wed, 23 Feb 2000, Marcus H. Mendenhall wrote:

If I boot with my zip drive (VST Zip) in the bay, I can read and
write from this drive.  If I then eject the Zip, insert a CD-ROM
drive, eject it, and re-insert the CD-ROM, I can only access the

(do you mean "re-insert the Zip"?)

drive as read-only.  Also, if I boot with the CD-ROM in, the Zi is
then read-only when inserted.

Hmmm... interesting.  I've never tried with a zip drive, I don't have one.

I have looked through a couple of spots in the kernel already, to wit:
drivers/macintosh/mediabay.c
drivers/block/ide-floppy.c (since the zip seems to be handled as a floppy)

An ATAPI floppy, yes, I would think.

and I cannot see where the decision is made as to whether a floppy
shows up as write-protected or not.  There is only one reference to
the wp flag, and at first glance, this wasn't even accessed.  I
supposed I could try to hack the flag to always-writable anytime a
zip is put in,  but this might then mishandle read-only zips (which I
have never checked if they work anyway).

Does anyone out there have enough intimate familiarity with the
drivers to know exactly where to poke?  (Paul M., are you listening?)

I'm not particularly familiar with the IDE driver code myself.  I would
need to trace through it to find out where things are going wrong.  A good
starting place would be to strace the mount command to see first of all
which system call is failing when you try to access it read-write.

A related question is whether the DMA capability should get turned on
for the zip.  Does it have the same capabilities as a regular IDE
drive, or is it really a lot more like a floppy in its interface?

Potentially it could do DMA.  You can find out with `hdparm -i /dev/hda'.

--
Paul Mackerras, Senior Open Source Researcher, Linuxcare, Inc.
+61 2 6262 8990 tel, +61 2 6262 8991 fax
paulus@linuxcare.com.au, http://www.linuxcare.com.au/
Linuxcare.  Support for the revolution.

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/