[Oberon] PO2013 - SD Image Tool

Charles Perkins chuck at kuracali.com
Sat May 16 17:24:29 CEST 2020

Thomas, Michael,

I did in fact write a fuse filesystem for the oberon fs into my go emulator
so that I could copy files into and out of a disk image from linux... it
worked, mostly. I learned a lot from that. I wouldn't try to use it as is,
it's too much of a mess but it could be instructive for someone who wants
to do it more cleanly.

My current effort is to take the basic logic from that and make a Linux
file system kernel module in C. Combining that with a QEMU emulator of the
RISC5 machine would be sweet, I think.


On Sat, May 16, 2020 at 7:54 AM Michael Schierl <schierlm at gmx.de> wrote:

> Am 16.05.2020 um 15:33 schrieb Tomas Kral:
> > On Sat, 16 May 2020 15:07:58 +0200
> > Michael Schierl <schierlm at gmx.de> wrote:
> >
> >> Nope. It should provide space for a FAT filesyste
> >
> > Possibly does not have to, looking at my humble backup/restore tool. I
> > just skip or seek past the FAT (256*1024K+1), and use 64MB only.
> 256*1024K = 256M and not 256K :-)
> > pi at raspberrypi:/usr/src/oberon/img $ ls -sh
> >
> > 424K RISC.FS   <=== original
> >  66M RISC1.FS  <=== my backups
> >  66M RISC2.FS
> >  66M RISC3.FS
> >  65M RISC4.FS
> Unlike the emulator, the real thing does not keep track which sectors
> have ever been written to, so if you want to make it simple, you have to
> copy the maximum size, which is 64 MB.
> If you would like to shrink your images, you can also add a command to
> Kernel.Mod which iterates over the sector map and overwrites every
> unused sector with 0 bytes. I believe this is a simple task that you are
> capable of doing, certainly easier than doing a full defragmentation.
> Once you ran that command, you can then cut off the image after the last
> non-empty sector. And you will notice if you compress the image that it
> compresses a lot better (as all those zeroes compress really well).
> > But you are right, it can only be used as OBERON.FS, cannot mount on as
> > FAT or EXT4, through USB port. Perhaps if Linux mount people added
> > Oberon FS then yes.
> There are efforts by Charles Perkins to add such a driver, you can see
> the progress at <https://github.com/io-core/obfs>. I never used it so I
> am unsure about the status (whether it even works). When I want to get
> all the files in an image to the host (and do not want to use HostFS for
> that), I usually copy a file list out of the emulator and feed that to
> PCLink to retrieve all the files.
> > I would like to be close to original size, as I never fill the whole
> > 64MB FS, but I store it with dd.
> Then probably you should use a different tool :-)
> https://unix.stackexchange.com/q/416767/330045
> Regards,
> Michael
> --
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