Date: Tue, 20 Oct 1998 14:19:54 -0600 (MDT) From: "Kenneth D. Merry" <ken@plutotech.com> To: asami@cs.berkeley.edu (Satoshi Asami) Cc: scsi@FreeBSD.ORG Subject: Re: for i in disks Message-ID: <199810202019.OAA05203@panzer.plutotech.com> In-Reply-To: <199810201143.EAA17327@silvia.hip.berkeley.edu> from Satoshi Asami at "Oct 20, 98 04:43:02 am"
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Satoshi Asami wrote...
> Hi folks,
>
> I'm thinking about implementing an "autorun"-like mechanism for disks.
> The idea is to have a script with a known name on a known position
> (say, partition `a' on the first BSD slice) which is called during
> boot. The script does something to set up the disk (mount some other
> partition, or set up a ccd, or something like that).
>
> However, to do this, I need to be able to write a loop in /etc/rc* to
> iterate through all available disks. I guess devfs when fully
> implemented will make this easy ("/devfs/da[0-9]*s?a"?) but my
> understanding is that it is not ready yet. I could try mounting all
> the nodes in /dev (the ones that are not available will presumably
> just fail) but with up to 96 disks per system, that could be a lot of
> failures.
>
> I could do something like
>
> grep 'da[^ ]* at ahc' /var/run/dmesg.boot
>
> but it sometimes overlaps other messages and it also appears to be
> very incomplete on some machines.
[ ... ]
> (There are 42 disks on this machine.)
>
> Any ideas?
>
> Satoshi (I know I know, one of these days I'll actually implement something)
Well, there are several ways you can do this. The first question is
whether you want to do this for just CAM-accessible disks, or for all disks
in the system.
If you just want a listing of CAM-accessible disks, I've attached a program
that will do that. 'camcontrol devlist' will also list all CAM devices.
The attached program takes as arguments the peripheral names you're
interested in. e.g.:
{roadwarrior:/usr/home/ken/src/camtest:41:0} ./devmatch da
da0
da1
{roadwarrior:/usr/home/ken/src/camtest:42:0} ./devmatch da cd
da0
da1
cd0
{roadwarrior:/usr/home/ken/src/camtest:43:0} ./devmatch da cd pass
da0
da1
cd0
pass0
pass1
pass2
It's also available here:
ftp://ftp.kdm.org/pub/FreeBSD/cam/devmatch.c
Notice that the peripheral names passed in are ORed in and compsed into a
matching expression. You can also do much more complicated matching
expressions if you want. (You can even match against inquiry patterns,
just like the kernel quirk matching code does.)
I plan on adding code similar to 'devmatch.c' to camcontrol at some point.
It'll hopefully take advantage of more of the transport layer matching
functionality, though.
If you want to get a listing of all disks, SCSI, IDE, etc., you'll need to
get that from the devstat(9) code. There's a program here to dump out all
the devstat structures:
ftp://ftp.kdm.org/pub/FreeBSD/cam/ds.c
The devstat structures have the device name and unit number for each
device. They also have flags indicating what type of device it is (direct
access, sequential access, cdrom), the interface (IDE, SCSI or other), and
whether or not it's a passthrough device. (The passthrough device flag
allows you to figure out what the underlying device type is, rather than
just that the peripheral driver in question is a passthrough driver.)
iostat(8), systat(1) and vmstat(8) use matching code from the devstat(3)
library to build matching expressions. You can probably look at the ds.c
program above, iostat, and the devstat library to get an idea of how to do
what you want to do using the devstat code.
So, depending on whether you want just SCSI disks, or all disks, there are
different alternatives you can use. And, unlike grepping through the
dmesg information, these actually give deterministic results. :)
Ken
--
Kenneth Merry
ken@plutotech.com
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