From: wkt@tuhs.org (Warren Toomey)
Subject: [Unix-jun72] mkfs.c is now working
Date: Mon, 5 May 2008 00:33:43 +1000 [thread overview]
Message-ID: <20080504143343.GA39542@minnie.tuhs.org> (raw)
All, my mkfs.c $Revision: 1.17 $, $Date: 2008/05/04 14:20:12 $ now produces
mountable filesystem images, and it's now checked into the svn repository.
The problem was that the size of a directory is not the size of the blocks
allocated to it, but is in fact the number of bytes of the in-use directory
entries. For example, / was being allocated 1 block == 512 bytes. But 512
is not its size (as it would be in later UNIXes); in fact if / has entries
41 sdrwr- 7 root 70 Jan 1 00:00:00 .
41 sdrwr- 7 root 70 Jan 1 00:00:00 ..
43 sdrwr- 2 root 570 Jan 1 00:00:00 bin
42 sdrwr- 2 root 250 Jan 1 00:00:00 dev
99 sdrwr- 2 root 100 Jan 1 00:00:00 etc
108 sdrwr- 2 root 70 Jan 1 00:00:00 tmp
114 sdrwr- 2 root 20 Jan 1 00:00:00 usr
then its size is 7 entries * 10 bytes each = 70 bytes.
Importantly, this also means that we can now make bootable root filesystems
without having to do a cold UNIX:
% tools/mkfs /usr/local/src/V1 rf0.dsk rf # Make the / disk
% tools/mkfs /usr/local/src/V1 rk0.dsk rk # Make the /usr disk, same stuff
% ./simh.cfg
PDP-11 simulator V3.7-3
./simh.cfg> #!tools/pdp11
Unknown command
Disabling CR
Disabling XQ
RF: buffering file in memory
TC0: 16b format, buffering file in memory
sim> g
:login: root
root
# /tmp/a.out
/dev/rk0# ls -l /usr/tmp
total 8
112 sxrwrw 1 root 156 Jan 1 00:00:00 a.out
110 sxrwrw 1 root 1664 Jan 1 00:00:00 etma
113 sxrwrw 1 root 6 Jan 1 00:00:00 hello
109 sxrwrw 1 root 26 Jan 1 00:00:00 ttmp
111 sxrwrw 1 root 142 Jan 1 00:00:00 utmp
# df
806+4602 # Number of free blocks on / and /usr
I added /usr/tmp/hello just to verify that I was getting files that
were not on the cold UNIX tape.
Cheers,
Warren
next reply other threads:[~2008-05-04 14:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-04 14:33 Warren Toomey [this message]
2008-05-04 14:42 ` Warren Toomey
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