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Date: Tue, 3 Jan 2012 00:42:20 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jack Stone <jwjstone@fastmail.fm>
Cc: Matthew Garrett <mjg@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Greg Kroah-Hartman <gregkh@suse.de>,
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Subject: Re: loading firmware while usermodehelper disabled.
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> Can we tell by the USB ids that this is a device that might need
> firmware and load it into memory anyway - it would use more memory but
> would always work as we would have the firmware.

Only by wasting a lot of memory in some cases. For the majority of cases
however yes you can take a good guess that id X might need firmware Y and
the firmware will only be a few K.

In that case however you don't want some generic firmware module knowing
all this crap, your driver can just request_firmware() the stuff as
modprobe and free it up on the module unload. For a typical 8bit firmware
of a few K you'll free a ton more memory unloading the module than the
firmware ! That I think actually covers the majority of devices under
discussion.

For the giant-firmware cases, it's unworkable on small devices - but they
are special cases anyway and almost entirely video - so not currently
ones that cause a problem unless you are doing RFC4824 in which case your
nearest asylum should be consulted.

Alan