[9fans] partition question

[9fans] partition question

[Tim Newsham]

Hi,
    I noticed the sd device (devsd, '#s') doesnt probe for partitions
itself, but relies on an external source for partitions.  Commands like
disk/prep -p and disk/fdisk -p can probe the disk to generate the commands
sd needs to populate the tables.  The /rc/bin/termrc has such fdisk and
prep commands.  What is confusing to me though is that I cant find a
similar instance for cpurc.  How are these tables populated in the cpu
case (9load through the getconf call that devsd makes?)?  Pointers to
where in the code to look would be appreciated.

Tim N.

Re: [9fans] partition question

[Richard Miller]

Some sd partitions are set up as a side effect of the bootstrap
process.  Look at mbrpart() in /sys/src/boot/pc/part.c, which
is called for each sd while probing for possible boot devices.

The comment says
/*
 * Fetch the first dos and all plan9 partitions out of the MBR partition table.
 * We return -1 if we did not find a plan9 partition.
 */
That's why termrc does further probing, to find any extra
partitions besides the above.  To do the same for a CPU server,
you would have to add something to the local cpurc.

-- Richard

Re: [9fans] partition question

[Russ Cox]

>     I noticed the sd device (devsd, '#s') doesnt probe for partitions
> itself, but relies on an external source for partitions.  Commands like
> disk/prep -p and disk/fdisk -p can probe the disk to generate the commands
> sd needs to populate the tables.  The /rc/bin/termrc has such fdisk and
> prep commands.  What is confusing to me though is that I cant find a
> similar instance for cpurc.  How are these tables populated in the cpu
> case (9load through the getconf call that devsd makes?)?  Pointers to
> where in the code to look would be appreciated.

In addition to what Richard said, there are no disks on our CPU servers. ;-)

[9fans] Partition question

[Jeremy English]

Hi,

This is my second time installing plan 9 and I ran into something 
strange. I have my hard drive divide into two partitions both of them 
fat32. When I did the install I delete the second partition, reformatted 
it and continued with the install. When I rebooted the BPB of my first 
partition had been changed. Well the OEM name and the BPB_FATSz32 had 
been changed. It looked like the BPB had been changed to FAT12. I was 
able to correct the value of fat size and all of the data was still on 
the first partition. So, it looks like the install just changed that 
part of the disk and left the rest alone.

Has anyone else had a similar problem?

Jeremy
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-- 
Dennis Davis, BUCS, University of Bath, Bath, BA2 7AY, UK
D.H.Davis@bath.ac.uk