Subj : Re: Computer Broken
To   : apam
From : tenser
Date : Tue Sep 16 2025 06:52 am

On 14 Sep 2025 at 08:58p, apam pondered and said...
 
 ap>  > Oh nice.  What's the problem that you hit?  Possibly you've already
 ap>  > fixed it by now, but I'm curious.
 ap> 
 ap> It was actually an issue with my memcmp function, i was comparing an
 ap> extra byte.. no idea how that one snuck by for so long!

Oh great!  It's surprising how long a small bug like that can
last, and how far you can still get while it does.

[snip]
 ap>  > a filesystem directly in a disk file and copy files into that; it
 ap>  > would be a fair bit of work, as you'd have to write code to write
 ap>  > the minix3 file structures into that file, versus letting the kernel
 ap>  > do that for you, but it would be very portable.  Of course, using
 ap>  > FAT would be much simpler.
 ap> 
 ap> Yeah, it's possible, but yeah, a lot of work, and filesystems are
 ap> something I struggle with a bit. I did think instead I could write a
 ap> minix3 FUSE driver, then it might port to use with FUSE on other systems.

Honestly, it's probably not worth it, and if you've got a working
fat implementation, then no need to bother.  It may be interesting,
though!

 ap> Fat is also much better, my minix 3 driver only supports 1024 block size,
 ap> which appears to make filesystems restricted to small sizes. I'm not sure
 ap> if thats an error on my part, as when I was writing it I understood that
 ap> they could only be 1024 block size, but I think that was incorrect.

The Minix filesystem is pretty, well, minimal, even for v3.  It looks
an awful lot like the 7th Edition Unix filesystem, or perhaps that FS's
incarnation as "S5" in System V.  Anyway, yeah, it allocates space in
chunks of "zones" (which are 1024-byte blocks), but it supports up to
a triply-indrect block, so you can allocate a pretty big number of
zones to a file; theoretically, maximum file sizes would be in the gigs.
However, the size field in the inode is a signed 32-bit integer, so in
practice any given file is limited to 2GiB or so.  You could stretch
the size out to 64 bits and bump the zone size up to 4KiB or so and
that would make more or less let you address TiB of space, but you
wouldn't be able to use any of the existing tools to manipulate the
filesystem externally.

 ap> Now that the FAT driver is working, I've been able to port all my scripts
 ap> to use FreeBSD, which is great, means I'm not stuck on Linux if I don't
 ap> want to be :)

Hey, that's great!  No need to futz around with the Minix3 FS, then.

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