Re: Adding PCMCIA support to the kernel tree -- developers needed.

[David Woodhouse <dwmw2@infradead.org>]

On Mon, 5 Feb 2001, David Brownell wrote:

> Serializing the order for event reports is a concern:  don't report
> unplugs before you report the plug-in of that device, keep the device
> identifiers stable.

Er... we can wait for arbitrary lengths of time in execve(). So events 
aren't serialised anyway, and cannot be if you report them by running a 
userspace helper like this. You'd have to have a queue which is read by a 
single userspace process (which could perhaps be spawned when the queue 
becomes non-empty).

> The "boot time events" are all lost unless they can be inferred
> from "usbdevfs" or (for PCI) "procfs".

Should be entirely feasible for a PCMCIA script to determine the devices 
present during boot too, rather than queuing the actual events, then.

> > If you wish to wait, why not wait for activation by sysctl ?
> 
> That is, sysctl to set the kernel "hotplug" string?  Would that
> then invoke "/sbin/hotplug start", or would something else
> need to make sure all the relevant subsystems are well enough
> initialized?

I assumed this meant the threads would be spawned and wait, as I 
suggested, but instead of waiting till the rootfs is mounted, they'd wait 
for an explicit trigger from userspace, whether that's setting the 
'hotplug' string or a new 'hotplug_trigger' sysctl. But that means we have 
kernel threads collecting waiting for userspace to trigger them, and I'm 
not sure that's a good idea.

-- 
dwmw2




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