* Re: On demand modules loading with {tmp,ram}fs and udev
2003-10-25 0:00 On demand modules loading with {tmp,ram}fs and udev Tomasz Torcz
@ 2003-10-25 0:42 ` Greg KH
2003-10-25 1:09 ` Tomasz Torcz
2003-10-28 18:31 ` Greg KH
2 siblings, 0 replies; 4+ messages in thread
From: Greg KH @ 2003-10-25 0:42 UTC (permalink / raw)
To: linux-hotplug
On Sat, Oct 25, 2003 at 02:00:18AM +0200, Tomasz Torcz wrote:
> Hi,
>
> I was thinking about small addition to tmpfs. When mounted with 'dev'
> option, any lookup of non existing file should result in calling
> modprobe with filename as argument.
> When coupled with mount tmpfs over /dev (or /udev) this functionality
> would allow on-demand module loading (as with devfs and plain old
> device nodes).
How will you do the mapping of /dev names to modules in kernel space?
How are you going to know which of the 50 or so sound drivers to load
when opening /dev/dsp?
And what's wrong with the current scheme of, "load a driver when the
device is seen"? This is how Linux currently works, and has been moving
to for quite some time. In the past we didn't have that capability, so
the "load the driver when we open the /dev node" hack was added.
Remember, the current size of most /dev trees is about 18 thousand
entries and growing...
thanks,
greg k-h
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: On demand modules loading with {tmp,ram}fs and udev
2003-10-25 0:00 On demand modules loading with {tmp,ram}fs and udev Tomasz Torcz
2003-10-25 0:42 ` Greg KH
@ 2003-10-25 1:09 ` Tomasz Torcz
2003-10-28 18:31 ` Greg KH
2 siblings, 0 replies; 4+ messages in thread
From: Tomasz Torcz @ 2003-10-25 1:09 UTC (permalink / raw)
To: linux-hotplug
On Fri, Oct 24, 2003 at 05:42:34PM -0700, Greg KH wrote:
> On Sat, Oct 25, 2003 at 02:00:18AM +0200, Tomasz Torcz wrote:
> > Hi,
> >
> > I was thinking about small addition to tmpfs. When mounted with 'dev'
> > option, any lookup of non existing file should result in calling
> > modprobe with filename as argument.
> > When coupled with mount tmpfs over /dev (or /udev) this functionality
> > would allow on-demand module loading (as with devfs and plain old
> > device nodes).
>
> How will you do the mapping of /dev names to modules in kernel space?
> How are you going to know which of the 50 or so sound drivers to load
> when opening /dev/dsp?
Just call modprobe. Modprobe will check /etc/modprobe.conf for dsp
aliases and load module. Then udev will make devnode.
> And what's wrong with the current scheme of, "load a driver when the
> device is seen"? This is how Linux currently works, and has been moving
> to for quite some time. In the past we didn't have that capability, so
> the "load the driver when we open the /dev node" hack was added.
Few days ago I did dd if=something of=/dev/floppy/0; then I saw
in logs that floppy module was loaded. That was because I use devfs
which run modprobe when it's needed.
With udev dd would fail with non-existant /dev/floppy/0. There
is no mechanism to call modprobe.
I'm also surprised that"load the driver when we open the /dev node"
is a hack. I get used to this standard Linux functionality as
something obvious. Other OSed (*BSD, Solaris etc.) don't work like
that?
--
Tomasz Torcz There exists no separation between gods and men:
zdzichu@irc.-nie.spam-.pl one blends softly casual into the other.
Please CC.
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: On demand modules loading with {tmp,ram}fs and udev
2003-10-25 0:00 On demand modules loading with {tmp,ram}fs and udev Tomasz Torcz
2003-10-25 0:42 ` Greg KH
2003-10-25 1:09 ` Tomasz Torcz
@ 2003-10-28 18:31 ` Greg KH
2 siblings, 0 replies; 4+ messages in thread
From: Greg KH @ 2003-10-28 18:31 UTC (permalink / raw)
To: linux-hotplug
On Sat, Oct 25, 2003 at 03:09:32AM +0200, Tomasz Torcz wrote:
> On Fri, Oct 24, 2003 at 05:42:34PM -0700, Greg KH wrote:
> > On Sat, Oct 25, 2003 at 02:00:18AM +0200, Tomasz Torcz wrote:
> > > Hi,
> > >
> > > I was thinking about small addition to tmpfs. When mounted with 'dev'
> > > option, any lookup of non existing file should result in calling
> > > modprobe with filename as argument.
> > > When coupled with mount tmpfs over /dev (or /udev) this functionality
> > > would allow on-demand module loading (as with devfs and plain old
> > > device nodes).
> >
> > How will you do the mapping of /dev names to modules in kernel space?
> > How are you going to know which of the 50 or so sound drivers to load
> > when opening /dev/dsp?
>
> Just call modprobe. Modprobe will check /etc/modprobe.conf for dsp
> aliases and load module. Then udev will make devnode.
Ok, that sounds reasonable. Looking forward to your ramfs
implementation that does this :)
> I'm also surprised that"load the driver when we open the /dev node"
> is a hack. I get used to this standard Linux functionality as
> something obvious. Other OSed (*BSD, Solaris etc.) don't work like
> that?
I do not know what other oses do in this regard, sorry.
greg k-h
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^ permalink raw reply [flat|nested] 4+ messages in thread