squeegee@well.UUCP (Stephen C. Gilardi) (05/20/91)
I am in search of RAM disk driver example code for BSD4.3. I've already
posted a similar request in comp.sys.next and comp.unix.internals... no
response yet. Here's why:
I have a NeXT computer with no floppy drive. I also have a Mac IIci running
A/UX with a floppy drive. Much of NeXT software distribution is now done on
UNIX format 1.44Meg floppies. A/UX can't MOUNT the NeXT floppies, but it CAN
read all the bytes off them using something like
cat /dev/rfloppy0 > flopdisk.image
I can move flopdisk.image over to the NeXT using Ethernet. I'd like to be
able to somehow mount that image as (perhaps) a read only block device. It
occurs to me that a RAM disk driver would be ideal here. I could make a
1.44Meg RAM disk. Assuming the driver supported both RAW and block I/O, I
could do:
cat flopdisk.image > /dev/rrd0a
mount /dev/rd0a /pseudofloppy
What I need from you folks is an example driver for BSD 4.3 based perhaps on
the template block driver in "Writing a UNIX device driver" by Egan and
Teixeira. I tried doing it myself, but it doesn't work. The NeXT seems to
have some different arguments to the driver entry points even than 4.3, but
a known good 4.3 RAM disk driver would be a GREAT starting point.
I asked in comp.sys.next, but didn't get any response in about a week. People
look at me funny when I ask for a UNIX ram disk ("You do after all have virtual
memory..."). I hope the above justifies my need. If anyone can think of
another way to do it I'd be pysched to hear it. I take it that if I was using
Suns I could use ND... NeXT even has major device numbers reserved for a
RAM disk's RAW and block I/O. They don't however seem to include the driver.
Any help would be appreciated!
--Steve
well!squeegee@apple.com (== squeegee@sf.ca.us)mouse@thunder.mcrcim.mcgill.edu (der Mouse) (05/24/91)
In article <9105200434.AA19778@well.sf.ca.us>, squeegee@well.UUCP (Stephen C. Gilardi) writes: > I am in search of RAM disk driver example code for BSD4.3. [...] I > have a NeXT computer with no floppy drive. Well, a NeXT is not 4.3; it's Mach with a 4.3 compatability layer slapped on. (It's a reasonably good layer at the syscall level, but it's a long way from 4.3 in terms of real use - full flamage available by mail.) I don't know for sure what their driver internals look like, but a quick look at a couple of include files makes it look as though their driver interface isn't too far from the Berkeley one. Just beware that a driver that works on 4.3 will not necessarily plug&play. > [...stuff on floppy...Mac IIci A/UX can read them...can get data file > on NeXT with floppy contents on it...] I'd like to be able to > somehow mount that image as (perhaps) a read only block device. A RAMdisk would solve this problem, yes. But you don't really need it. The filesystem format is really not complicated. If the floppy filesystem format is the normal Berkeley filesystem format, I have programs I wrote that I can send you that are capable of reading stuff off of it, given the disk contents, even in a file. Don't you just love binary distributions? :-( der Mouse old: mcgill-vision!mouse new: mouse@larry.mcrcim.mcgill.edu