[9fans] mounting a 9660 file system - writeable

[9fans] mounting a 9660 file system - writeable

[Conor Williams]

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hello there 9fans_ears...
i create a file system pretty much simply on my vm by
% *cat* 9frontXYZ.iso > /dev/sdC0/data
and that works pretty well and boots a p9 vm from C
but... I cannot create a dir (only in /tmp), so...I have tried:
% *mkdir* /tmp/C
% *9660srv*
% *mount* -c /srv/9660 /tmp/C /dev/sdC0/data
% *mkdir */tmp/C/conors_source_code_al
but it is still not writeable... yes! there are binds but
I need a perm. % *mkdir* /tmp/C/conors_source_code_et_al
effectively % *mkdi*r /conors_source_code_et
as /tmp/ disappears each time I boot - /c 12:03-080723

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Re: [9fans] mounting a 9660 file system - writeable

[Dave Eckhardt]

9660srv's job is to serve the files stored on a CD-ROM.  CD-ROMs
are more or less read-only, so 9660srv serves the files as read-only
as well.

In most setups, the /tmp file system is "stored" in RAM.  It's faster
than sending the data to some storage device, and when you turn the
machine off the files vanish, which matches the mental model people
sometimes use when putting things in /tmp.

If you want to write files that persist across reboots, you'll need
to use some other kind of file system (and give it a storage
partition).  Assuming you're using 9front, you might start looking
somewhere around here:

  https://fqa.9front.org/fqa7.html#7.1.2

You might give your VM two storage devices, one blank and one holding
the ISO image; running the installer on the ISO image would guide
you through installing a regular read/write file system on the other
storage device.

If you wanted to layer your changes on top of an underlying CD-ROM
image, that could be done with an overlay file system.  One of my
students wrote one many years ago:

  http://9p.io/wiki/plan9/divergefs/

Later other students used it to build kernels without write access
to /sys/src -- their overlay contained their source changes and
also their object files.  The overlay file system will still need
somewhere to store files, though.

Dave Eckhardt

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Re: [9fans] mounting a 9660 file system - writeable

[Conor Williams]

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thanks Dave... will look into the overlay file system + kernel hack soun..

got the 9front booting off one 9660 drive now (50GB) and am
mounting my second 20GB drive into /tmp/D (its a 9fat partition)
and i have rebooted and the created D files are still there

one strange thing that bogged me down for most of today (and stopped
me emailing you earlier), was that I edited the .iso, lets call it
cwCON.iso
and catted that to /dev/sdC0/data and no matter what I did it would not
boot,
the fs was there, but no booting...

what I am after doing is reverting to the current 9front iso just 20 mins
ago and it worked perfectly, so somehow they created 3 partitions
in /dev/sdC0/data (a 486MB, a 1MB ESP (1 cylinder)
and another large file system) (using cat???) so... my next post is
going to wonder how they did that and how i can add some handy
scripts to my own version of their iso... (is /386/pbslba somethingp...)

ps: is a 20GB file system safe? r why should i use fossil??
Kind Regards... & happy summer Dave... /c@midnight+43mi

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