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

["Adam J. Richter" <adam@yggdrasil.com>]

>> 	I said, "scan the bus *after* initializing the hot plugging
>> support and deal with devices that are already plugged in [...]"
>> You may process a device twice this way, but user level software
>> can detect this and synchronize when this is really necessary.  In
>> most cases, you just want to modprobe a module, which can safely be
>> done multiple times, so it is not necessary to bother checking.

>The problem is that may try to configure a device that's no longer there,
>or worse a device that is being replaced this way. You need to tell the 
>kernel that it must cease processing events on a bus that you are scanning.

	Firstly, that would also happen if you queue the hot plugging
events.  Secondly, this situation is detectable by the user level
initialization script failing (in the dhcp example, dhclient would get
an error).  It is easy enough to have the initialization script
release the locking resource when that happens (in my example, by
doing an "rm -rf /var/run/$netif").

	Even for the more elaborate case, where, say, a user quickly
inserts an ethernet card, removes it and then inserts a wireless
ethernet card which might need a different initialization, my scheme
would get it right because it does not look for existing devices until
it has already initialized the hot plug event handling, since the only
way that the first card could be detected is if the hot plugging
facilties were in place in time to see its later removal and the
insertion of the new card.

Adam J. Richter     __     ______________   4880 Stevens Creek Blvd, Suite 104
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