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Date:      Fri, 21 Oct 2005 20:23:58 +0200
From:      Gordon Bergling <gbergling@0xfce3.net>
To:        freebsd-hackers@freebsd.org
Subject:   locking of a subsystem (remove of spl calls)
Message-ID:  <20051021182358.GA11009@node26.0xfce3.net>

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Hi,

I am about to write a special display driver, which should be something
like a framebuffer device, in terms of FreeBSD.

I whould like to make this driver from at the beginning MPSAFE, but I am
not sure that this is possible. Looking at some devices in sys/dev/fb and
sys/dev/syscons there are a lot of spl calls with make these drivers
require GIANT.

My question is now where to start.

Should I write my driver with spl calls or is there an MPSAFE way which
could I take?

And while I am here how hard whould it to get the looking of syscons
right. I have studied the source code for a while now and could take
this part. I am not sure about the other kernel subsystems like tty for
example. Whould it be possible to lock down syscons and maybe some
device in sys/dev/fb without a complete GIANT removal from the tty
subsystem?

best regards,

	Gordon

-- 
Gordon Bergling <GBergling at 0xfce3.net>	      http://www.0xFCE3.net/
PGP Fingerprint:  7732 9BB1 5013 AE8B E42C  28E0 93B9 D32B C76F 02A0
RIPE-HDL: MDTP-RIPE			"There is no place like 127.0.0.0/8"



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