Subject: Re: PATCH: Export console functions for use
	by	Software	Suspend	nice display
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: ncunningham@users.sourceforge.net
Cc: Daniel Jacobowitz <dan@debian.org>, viro@parcelfarce.linux.theplanet.co.uk,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Date: Fri, 23 Jan 2004 14:12:51 +1100
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On Fri, 2004-01-23 at 14:07, Nigel Cunningham wrote:
> Hi.
> 
> On Fri, 2004-01-23 at 15:49, Benjamin Herrenschmidt wrote:
> > Also, by using write instead of blasting the low level code,
> > you will not have to worry about locking issues. (The way
> > you tap the low level stuff should require at least the console
> > semaphore held, write to /dev/console don't)
> > 
> > Ben
> 
> Locking is not an issue. This is suspend-to-disk. Everything else is
> stopped while we're working.

No. You can still get a printk from irq... 

> By the way, am I understanding the suggestion correctly? Do you
> (collective) mean getting a fd for /dev/console from within kernel code
> and using that? I've been looking at the way printk works and wondering
> if con->write is equivalent (once I find the right console to write to)?

Yes. get an fd and write to it. grep for write to find other uses :)

You may have to be a bit careful about what context you are in, but I
suppose it's whatever userland process triggered the sleep in the
first place, no ? For load, it's probably whatever process did swapon ?

In both cases, it should be fine.

Ben.


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