overview of using hotplug in initrd

overview of using hotplug in initrd

[Dan Barber]

Hello,

Can someone point me to an overview or HOWTO in using hotplug in initrd 
for discovering hardware on boot up?

thanks,

Dan


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Re: overview of using hotplug in initrd

[Marco d'Itri]

On Feb 22, Dan Barber <dan@mutagenix.org> wrote:

> Can someone point me to an overview or HOWTO in using hotplug in initrd 
> for discovering hardware on boot up?
You don't, nowadays you are supposed to use udev and an initramfs.

-- 
ciao,
Marco


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Re: overview of using hotplug in initrd

[Chris Smith]

>>>>> "Marco" = Marco d'Itri <md@Linux.IT> writes:

    Marco> On Feb 22, Dan Barber <dan@mutagenix.org> wrote:
    >> Can someone point me to an overview or HOWTO in using hotplug
    >> in initrd for discovering hardware on boot up?
    Marco> You don't, nowadays you are supposed to use udev and an
    Marco> initramfs.

Is there a reference implementation of how that should be done?  I
used some ancient stuff to traverse /sys and make nodes for my block
devices, but the resulting boot was very messy.  What is Teh 'Right'
Way To Do It?
Best,
Chris



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Re: overview of using hotplug in initrd

[marrandy]

On Wednesday 22 February 2006 17:47, Chris Smith wrote:
> >>>>> "Marco" = Marco d'Itri <md@Linux.IT> writes:
>
>     Marco> On Feb 22, Dan Barber <dan@mutagenix.org> wrote:
>     >> Can someone point me to an overview or HOWTO in using hotplug
>     >> in initrd for discovering hardware on boot up?
>
>     Marco> You don't, nowadays you are supposed to use udev and an
>     Marco> initramfs.
>
> Is there a reference implementation of how that should be done?  I
> used some ancient stuff to traverse /sys and make nodes for my block
> devices, but the resulting boot was very messy.  What is Teh 'Right'
> Way To Do It?
> Best,
> Chris


What's up with your clock.  It's Friday, not Wednesday.  Please fix it.


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Re: overview of using hotplug in initrd

[David Gómez]

Hi Chris ;),

On Feb 22 at 05:47:26, Chris Smith wrote:
> Is there a reference implementation of how that should be done?  I
> used some ancient stuff to traverse /sys and make nodes for my block
> devices, but the resulting boot was very messy.  What is Teh 'Right'
> Way To Do It?

I believe is udevsynthesize, but it's difficult to get it except in an
old post in this list.

Personally i've found out that a 'find' command combined with
'echo "add" > uevent' and a recent kernel does a very good work ;).
If you only are interested in block devices it'd be enough to run
the find in /sys/block

regards,

-- 
David Gómez                                      Jabber ID: davidge@jabber.org


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Re: overview of using hotplug in initrd

[iSteve]

> Can someone point me to an overview or HOWTO in using hotplug in initrd 
> for discovering hardware on boot up?

I'm sure I'll be shouted at for being obsolete, but my way, in InitRD, is to use
now discontinued hotplug-ng (courtesy of Greg Kroah-Hartman, whom I thank for
great software) for hotplugging and to detect existing hw, I use: for als in
`cat /sys/bus/*/devices/*/modalias`; do modprobe $als; done
-- 
 -- iSteve


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Re: overview of using hotplug in initrd

[Aaron Griffin]

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On 2/25/06, iSteve <isteve@rulez.cz> wrote:> I'm sure I'll be shouted at for being obsolete, but my way, in InitRD, is to use> now discontinued hotplug-ng (courtesy of Greg Kroah-Hartman, whom I thank for> great software) for hotplugging and to detect existing hw, I use: for als in> `cat /sys/bus/*/devices/*/modalias`; do modprobe $als; done
Hmmm, that works for you?  Here, I loop over/sys/bus/pci/devices/*/modalias and then do some ide/scsi specificdetection.  That is, I have no support for that stuff built into thekernel (you may be different).Also, it's a hair faster to build a module string in a loop and call"modprobe -a", as modprobe only needs to read the config files once,thus one call is better than ~10.
iSteve, I'm curious as to your startup times, mine seem a tad slow,and I'd be interested in profiling this sort of stuff to make itfaster.ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÓ†+\x12\x17ó^µéšŠX¬²š'²ŠÞu¼±<Âÿjèºw[­æ¤Šx,r¸©¶)à•©à¹¨\x1e¶\x16­{^[^Û\x1a¦™bq«b¢{"žÚ0y¶§vj^[ŠW¦yØšü\vmzwm…éb½ì\x1emƬµ©ÝŽˆ§¶\x17©®)žuëÞ–Š^®èº–ëy©"ž\b§¶‹aŠÉÞÁÊ\x1dŠx-zºâ¶Šòþ^[m§ÿÿ±éÿjÏî³÷Ú–F þw­þÇ¥ýɝþH÷Žÿn'ۍ{ÛOÝjÛ^¸Ûÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ.)îÇøh¶™nƒ÷^½éfj)bž	b²Øm¶ŸÿþX§»\x1fá¢Úeº\x0fì¢êÜyú+ïçzÒâžìÿ†‹i–èÿuëÞ—ùb²Ûÿ²‹«qçè®\aÿëa¶ÚlÿÿåŠËlþÊ.­ÇŸ¢¸\x1eþw­þX¬¶ÏåŠËbú?–)îÇøh¶™nƒ÷^

Re: overview of using hotplug in initrd

[iSteve]

On Mon, 27 Feb 2006 12:06:31 -0600
"Aaron Griffin" <aaronmgriffin@gmail.com> wrote:

> On 2/25/06, iSteve <isteve@rulez.cz> wrote:
> > I'm sure I'll be shouted at for being obsolete, but my way, in InitRD, is
> > to use now discontinued hotplug-ng (courtesy of Greg Kroah-Hartman, whom I
> > thank for great software) for hotplugging and to detect existing hw, I use:
> > for als in `cat /sys/bus/*/devices/*/modalias`; do modprobe $als; done
> 
> Hmmm, that works for you?  Here, I loop over
> /sys/bus/pci/devices/*/modalias and then do some ide/scsi specific
> detection.  That is, I have no support for that stuff built into the
> kernel (you may be different).
> Also, it's a hair faster to build a module string in a loop and call
> "modprobe -a", as modprobe only needs to read the config files once,
> thus one call is better than ~10.
> 
> iSteve, I'm curious as to your startup times, mine seem a tad slow,
> and I'd be interested in profiling this sort of stuff to make it
> faster.

Fast. With a generic, very very modular kernel, it spends only about two or
three seconds in initrd; most of the time is taken by IDE drives detection.

I, however, use a significant trick; I run the modprobes in a paralel fashion,
since the I/O wait is what takes so long.

 -- iSteve


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Re: overview of using hotplug in initrd

[Aaron Griffin]

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On 2/27/06, iSteve <isteve@rulez.cz> wrote:> On Mon, 27 Feb 2006 12:06:31 -0600> "Aaron Griffin" <aaronmgriffin@gmail.com> wrote:>> > On 2/25/06, iSteve <isteve@rulez.cz> wrote:> > > I'm sure I'll be shouted at for being obsolete, but my way, in InitRD, is> > > to use now discontinued hotplug-ng (courtesy of Greg Kroah-Hartman, whom I> > > thank for great software) for hotplugging and to detect existing hw, I use:> > > for als in `cat /sys/bus/*/devices/*/modalias`; do modprobe $als; done> >> > Hmmm, that works for you?  Here, I loop over> > /sys/bus/pci/devices/*/modalias and then do some ide/scsi specific> > detection.  That is, I have no support for that stuff built into the> > kernel (you may be different).> > Also, it's a hair faster to build a module string in a loop and call> > "modprobe -a", as modprobe only needs to read the config files once,> > thus one call is better than ~10.> >> > iSteve, I'm curious as to your startup times, mine seem a tad slow,> > and I'd be interested in profiling this sort of stuff to make it> > faster.>> Fast. With a generic, very very modular kernel, it spends only about two or> three seconds in initrd; most of the time is taken by IDE drives detection.>> I, however, use a significant trick; I run the modprobes in a paralel fashion,> since the I/O wait is what takes so long.
Yeah, that's what I was debating doing, but I wasn't sure if thetimings would match up.  Could you send me a copy of your init script? I'd like to take a peek at it.
Thanks,AaronÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÓ†+\x12\x17ó^µéšŠX¬²š'²ŠÞu¼±<Âÿjèºw[­æ¤Šx,r¸©¶)à•©à¹¨\x1e¶\x16­{^[^Û\x1a¦™bq«b¢{"žÚ0y¶§vj^[ŠW¦yØšü\vmzwm…éb½ì\x1emƬµ©ÝŽˆ§¶\x17©®)žuëÞ–Š^®èº–ëy©"ž\b§¶‹aŠÉÞÁÊ\x1dŠx-zºâ¶Šòþ^[m§ÿÿ±éÿjÏî³÷Ú–F þw­þÇ¥ýɝþH÷Žÿn'ۍ{ÛOÝjÛ^¸Ûÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ.)îÇøh¶™nƒ÷^½éfj)bž	b²Øm¶ŸÿþX§»\x1fá¢Úeº\x0fì¢êÜyú+ïçzÒâžìÿ†‹i–èÿuëÞ—ùb²Ûÿ²‹«qçè®\aÿëa¶ÚlÿÿåŠËlþÊ.­ÇŸ¢¸\x1eþw­þX¬¶ÏåŠËbú?–)îÇøh¶™nƒ÷^