Re: Non-hardware devices like loop: another idea

["Alexander E. Patrakov" <patrakov@ums.usu.ru>]

Greg KH wrote:

>On Fri, Mar 12, 2004 at 08:03:00PM +0500, Alexander E. Patrakov wrote:
>  
>
>>I found my implementation rather clumsy and while implementing it I decided 
>>that it would be better to just mark such modules and modprobe tham all, and 
>>make the hotplug script modprobe other stuff. I decided to start implementing 
>>such mark... and found that it has already been done, so actually no patches 
>>are needed except for the udev initscript!
>>
>>I am talking about /lib/modules/<version>/modules.alias.
>>    
>>
>
>Take a look at a distro's modules.alias file.  With your scheme you
>would have them load every possible module.  Not a good idea :)
>  
>
Did that (both for Debian distribution and for the kernel source - 
grepped for MODULE_*ALIAS*'es that result in char-major or block-major 
entry in the modules.alias file). The junk is:
1) watchdog timers - they share the same alias which is not a good thing 
anyway
2) old cdroms like sbpcd - they won't load anyway on my computer
3) dv1394 and friends - we do need to blacklist them

Missing things are:
1) psmouse
2) ide-cd
3) maybe ACPI, but it is not accessible via /dev and therefore it is of 
no interest to udev

So maybe we do need to mark such software-only modules via special 
entries in .modinfo sections and not rely upon existing *major aliases. 
The idea remains the same: probe all modules with such mark set. I 
proposed to (mis-)use the presence of *major alias as such a mark.

Yes, I agree that not everybody needs the nbd module and with my 
approach, it will get loaded. But we already disagree with loading the 
module upon demand from an application accessing the non-existing device 
node, and therefore we have either to load the module at boot time or 
not to load it at all.

Oh, there is also a possibility of utilizing these char-major aliases 
for autoloading modules on demand with device nodes being already 
created, and this is what my earlier clumsy approach is about. Do you 
want to see my module-init-tools and kernel patches for that approach?

-- 
Alexander E. Patrakov



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