devfs and bootscripts...

Plasmatic plasmatic at
Thu Oct 4 14:01:17 PDT 2001

10/2/01 10:58:45 PM, Øyvind Repvik <mlists at> wrote:

>devfsd creates the 'normal' devices in case something breaks. AFAIK, most 
>stuff don't need devfsd any longer, and I haven't had problems with it 
>(Except that I've had to fiddle a bit with configuration)

Actually, from reading the devfs webpage and his explanation of the entire system, as I understand it devfsd servers two important purposes.

1) It makes it possible to have completely dynamic loading of devices, including making symlinks, loading modules, and running any other 
commands when a device is opened/closed.  This means that you don't have to run modload by itself, that you don't have to wait for a module 
to be cleaned, etc.

2) According to his page, the default devfs naming scheme is NOT intended to be used as-is.  It is merely a way of clearly seeing what device 
exists where (/dev/discs/disc0/part1 meaning the first partition on the first disc, as part of the group named 'disks').  He specifically states that 
devfsd is supposed to be used to change this naming scheme to anything you see fit (sounds like an LFS thing to me!)  The default action of 
devfsd is to recreate the original kernel naming scheme just to make the transition easier.  Even this is not entirely meant to be used by itself.  
Either of these 'can' be used, but the entire idea is to make up your own.

So, it still comes down to the same deal.  If you don't want to use it, you don't have to.  In fact, it MAY be possible to change the source code 
of devfs to hardwire your own naming scheme (don't see why not).  If you just want the dynamic abilities of devfs (like using devices on a R/O 
root like a CDROM) then maybe devfs is fine as is.  However, it was designed as such, and would probably be easier to use, with devfsd 
loaded, as this is the complement to the entire devfs.  As he explains it, the devfsd doesn't kill much for resources, as it's only active when 
loading/unloading devices (which shouldn't be done very often) and the amount of memory it takes is negligable (like 47 bytes per device, 
which, atleast on my system, is only a handful).

So in the end, it isn't even a matter of "can I afford the resources?"  But merely just a matter of personal tastes.  Do you want some of the 
capabilities, or would you rather have one less thing loaded in running?  Your choice.  After all, it's LFS :)



Note: The above are the thoughts, feelings, and reasonings of the author.  There may be errors or illogical reasoning involved.  If you happen to 
find any such errors, please correct them politely instead of flaming.  The author doesn't own any asbestos and would prefer to keep it that way 

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