From: Oliver Neukum <oliver@neukum.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: loading firmware while usermodehelper disabled.
Date: Tue, 3 Jan 2012 12:57:47 +0100
Cc: Jack Stone <jwjstone@fastmail.fm>,
	Matthew Garrett <mjg@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	Dave Jones <davej@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Larry Finger <Larry.Finger@lwfinger.net>,
	Chaoming Li <chaoming_li@realsil.com.cn>,
	"John W. Linville" <linville@tuxdriver.com>,
	"Greg Kroah-Hartman" <gregkh@suse.de>,
	USB list <linux-usb@vger.kernel.org>,
	Linux Wireless List <linux-wireless@vger.kernel.org>
References: <Pine.LNX.4.44L0.1201021041550.10702-100000@netrider.rowland.org> <4F0220F5.30309@fastmail.fm> <20120103004220.084d61f3@pyramind.ukuu.org.uk>
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Am Dienstag, 3. Januar 2012, 01:42:20 schrieb Alan Cox:
> 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.

I am afraid it doesn't, at least not fully.
We have many devices whose primary (operational) driver does not load
the firmware. That job is left to a secondary driver or user space.

We could leave those secondary drivers and their firmware in RAM after
their primary usage and except for a few pathological cases (which
can be solved with a few udev rules preventively loading drivers) we'd
be good, but we lack a mechanism for switching to a seconary driver
and back during resumption.

	Regards
		Oliver