Subject: Re: config(8) vs Brett Lymn :-)
To: John Kohl <jtk@atria.com>
From: Brett Lymn <blymn@awadi.com.au>
List: tech-kern
Date: 03/06/1997 13:44:39
According to John Kohl:
>
>In fact, I have hacked on config to do this sort of thing--I have it
>spit out #define'ed locator indices for indexing into cf_loc[], a list
>of locator names { "foo", "bar" }, and a count of locators. I haven't
>done any work to actually use this set of defines, though :)
>
Hmmmm can you send me the code? I would like to have a look at it.
As Der Mouse said, I am at the moment just running dmesg and picking
out the locators from the devices that I recognise (i.e. ones that I
picked up surfing the kernel data). This works ok on the machines I
have tested it on (i386 architecture) but I can see a couple of
problems with it:
1) the kernel message buffer is a fixed size and can, therefore, lose
the information I am surfing for if/when more kernel messages are
logged.
2) I am not 100% sure that the logging of a line is atomic - is the
whole line logged to the buffer without interruption? If it is not
then information could be corrupted by an ill-timed message.
One thing I did notice with the locators array was that it appeared to
be updated during the probe, well in the driver I looked at (fdc) the
locators were updated. Would this be a good place to pick the data
from? What about config lines of the sort
sd* at scsibus* target ? lun ?
I would imagine that the locators get overwritten on subsequent
probes? The other problem I have with the locators array is that the
contents are very bus specific which means I would need to know what
bus the device is attached to to sensibly interpret them. I think I
can pick up that information from the same files that config(8) uses.
I want to make this thing as architecture & bus neutral as I can and
where I cannot make it cope easily with new architectures & busses.
Finally, the prtconf is really only the start of another project -
automating the config file building itself, the data required to do
this is the same stuff that prtconf gets - along with a lot more. I
have roughed out some design for this, if anyone is interested they
are welcome to have a look.
--
Brett Lymn, Computer Systems Administrator, AWA Defence Industries
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