Re: [9fans] mechanism to bind partitions in /dev?

[Steven Stallion <sstallion@gmail.com>]

On Fri, Jan 17, 2014 at 10:57 PM, Yoann Padioleau <pad@fb.com> wrote:
> Hi,
>
> Can someone explain how the partitions in /dev/sdC0/xxx are populated? Who
> create those device files? I have a small plan9 kernel running a small shell (sh.Z)
> in memory and when I do  'bind #S/sdC0 /dev/' I just see the 'data', 'ctl', and 'raw' files.
> There is no 9fat or plan9 or whatever partitions there is on this disk. In fact I've
> tried to make on MACos via the Utility disk some fat images and when I do
> qemu -hdb dosdisk.img I can not access again the fat partition on this disk
> (I've tried dossrv and then mount /srv/dos/ /mnt #sdC1/data but it does not work).
> I can access it though when it's on a floppy disk (mount /srv/dos /mnt /dev/fd0disk
> works). How fd0disk is different from #sdC1/data?

Hi Yoann,

sdC0 and friends are populated by devsd (#S) as a part of some
bootstrap goop. What you will typically find is that only the
drive/partitions used to boot are populated, this is the reason for
the readparts= plan9.ini variable. There are other ways to prompt
devsd to create fs entries at boot - I'd suggest looking through
/sys/src/9/port/devsd.c.

Steve