Messages in this thread | | | Date | Thu, 19 May 2005 01:00:06 +0200 | From | Per Svennerbrandt <> | Subject | Re: [ANNOUNCE] hotplug-ng 002 release |
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* Per Liden (per@fukt.bth.se) wrote: > On Mon, 9 May 2005, Per Svennerbrandt wrote: > > > * Per Liden (per@fukt.bth.se) wrote: > > > On Fri, 6 May 2005, Greg KH wrote: > > > > > > [...] > > > > Now, with the 2.6.12-rc3 kernel, and a patch for module-init-tools, the > > > > USB hotplug program can be written with a simple one line shell script: > > > > modprobe $MODALIAS > > > > > > Nice, but why not just convert all this to a call to > > > request_module($MODALIAS)? Seems to me like the natural thing to do. > > > > I actually have a pretty hackish proof-of-consept patch that does > > basicly that, and have been running it on my systems for the past five > > months or so, if anybody's interested. > > Ah! Please post the patches.
Ok, so I finally decided that it's probably silly of me to hold of a working patch just because I wanted my first submission to the kernel to somehow be a marvellous example of ellegancy and not just some quick hack that I threw toghether as a personal proof-of-consept.
> > Along with it I also have a patch witch exports the module aliases for > > PCI and USB devices through sysfs. With it the "coldplugging" of a > > system (module wise) can be reduced to pretty much: > > > > #!/bin/sh > > > > for DEV in /sys/bus/{pci,usb}/devices/*; do > > modprobe `cat $DEV/modalias` > > done > > Nice! This is really what coldplugging _should_ look like. Hmm, maybe > even coldplug the system by request_module()'ing those as well at some > stage?
Well, the code already generates all the requests necessary. :) The only problem now of course beeing that it generates those at a "stage" ;) when userspace usually isn't ready to fullfill those.
I'm currently thinking about maybe making all the requests sleep on a waitqueue untill the root filesystem becomes availible, shoudn't be too hard if I remember the code correctly... Could potentialy end up using a lot of resourses though.
And, yeah, I know this could all be done quite easily with scripts in a initrd or similar, but that is in fact *exactly* what I'm trying to avoid here, to reduce complexity and keep thinks as simple as they possibly can be. I'm not proposing this as a generic solution for everyone, rather the opposite in fact. I do however beleve there to be enough demand out there for this particular kind of "special case" to warrant (optional) support for it in the mainline kernel.
> > (And I actually run exactly that on my laptop, and it works surpricingly > > well. (Largly due to the fact that the usb-controller is always attached > > below the pci-bus of course, but it really wouldn't take that much work > > to make it do the right thing even without relying on any specific > > ordering/topology)) > > > > With the above in place my system does all the module-loading that I > > care about automaticly, and most importantly does so without relying > > on an /etc/hotplug/ dir with everything and it's grandma in it (or at > > least thousands of lines of shellscripting). > > This is exactly what I'm looking for as well.
For example, I see absolutely no need for a fullblown hotplug system on my minimalst-userspace router/firewall. I just want the kernel to be able to load the right modules, on demand, as it boots (and perhaps when I plug in a usb flashdrive, every third, or so, year).
> > But since the request_modalias() thing seemed as such an obvious thing > > to do I have been reluctant to submit it fearing that I must have missed > > some fundamental flaw in it or you guys would have implemented it that > > way a long time ago? (at least since Rusty rewrote the module > > loader). Was I wrong*? > > > > Greg, Rusty, what do you think? > > I'd like to get a better understanding of that as well. Why invent a > second on demand module loader when we have kmod? The current approach > feels like a step back to something very similar to the old kerneld. > > /Per L
Sorry for the delay, patches to follow.
/ Per Svennerbrandt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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