Re: Non-hardware devices like loop: another idea

[Mike Snitzer <msnitzer@lnxi.com>]

What if you configure this options into the kernel, e.g.:

CONFIG_BLK_DEV_LOOP=y
CONFIG_TUN=y
... etc ...

rather than building all non-hardware backed devices as modules?  Relying
on them being modules seems quite restrictive.

Mike


On Fri, Mar 12 2004 at 08:03,
Alexander E. Patrakov <patrakov@ums.usu.ru> wrote:

> Recently I stated that I am working on solution to the "chicken-and-egg" 
> problem related to devices like /dev/loop*, /dev/nbd*, /dev/ppp and so on, 
> which require no hardware and therefore are not detectable by the hotplug 
> scripts.
> 
> My (bad) idea was to include the sysfs entries that would appear after loading 
> the module in the module itself by means of the MODULE_INFO macro, and then 
> modify depmod to populate /lib/modules/<version>/sys and use it to 
> populate /dev with the corresponding entries (the UDEV_TEST environment 
> variable already allows us to override the location of the sysfs directory). 
> Then the char-major magic will load these modules on demand.
> 
> I have a proof-of-concept implementation (will mail it here if there is any 
> demand). The list of files altered:
> 
> module-init-tools-3.0-pre5/depmod.c
> linux-2.6.4/include/linux/module.h
> linux-2.6.4/drivers/block/loop.c
> linux-2.6.4/drivers/char/rtc.c
> linux-2.6.4/drivers/net/ppp_generic.c
> ...and my udev initscript
> 
> This is not a real, but a proof-of-concept implementation because there are 
> much more such non-hardware modules. This works,
> 
> --- BUT! ---
> 
> 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.
> 
> The simple idea is to grep this file (and probably /etc/modprobe.conf also) 
> for lines containing char-major and block-major. The list pretty much 
> coincides with the list of non-hardware-related modules that nevertheless 
> provide devices.
> 
> Does anyone care to include this into the future release of udev?
> 
> -- 
> Alexander E. Patrakov
> 
> 
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