From: Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>
To: "Dmitry A. Fedorov" <D.A.Fedorov@inp.nsk.su>,
Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Balbir Singh <balbir_soni@yahoo.com>, linux-kernel@vger.kernel.org
Subject: Re: Is it useful to support user level drivers
Date: Thu, 21 Jun 2001 15:24:39 +0200 [thread overview]
Message-ID: <01062115243900.01881@idun> (raw)
In-Reply-To: <Pine.SGI.4.10.10106211905030.3193032-100000@Sky.inp.nsk.su>
In-Reply-To: <Pine.SGI.4.10.10106211905030.3193032-100000@Sky.inp.nsk.su>
> > The problem is that the IRQ has to be cleared in kernel space, because
> > otherwise you may deadlock.
>
> It depends on device type. Good designed ones does not raises a new
> interrupt until an explicit acknowledge by I/O from [user space] driver
> will be received.
>
> Access to device's ports and IRQs from user space is subject
> of system admistration policy so direct access to a dangerous devices
> should not be allowed.
>
> Lastly an IRQ kernel module can disable_irq() from interrupt handler
> and enable it again only on explicit acknowledge from user.
Unless you need that interrupt to be enabled to deliver the signal or let
userspace reenable the interrupt.
In addition, how do you handle shared interrupts ?
Regards
Oliver
next prev parent reply other threads:[~2001-06-21 13:27 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-21 10:41 Is it useful to support user level drivers Balbir Singh
2001-06-21 10:55 ` Tim Waugh
2001-06-21 11:04 ` Alan Cox
2001-06-21 12:43 ` Balbir Singh
2001-06-21 13:27 ` Alan Cox
2001-06-28 22:52 ` Pavel Machek
2001-06-21 12:45 ` Dmitry A. Fedorov
2001-06-21 13:24 ` Oliver Neukum [this message]
2001-06-21 14:46 ` Dmitry A. Fedorov
2001-06-21 15:19 ` Oliver Neukum
2001-06-22 4:19 ` Dmitry A. Fedorov
2001-06-22 7:28 ` Balbir Singh
2001-06-21 16:34 ` Abramo Bagnara
2001-06-21 17:27 ` Alan Cox
2001-06-21 19:59 ` Abramo Bagnara
2001-06-21 20:40 ` Richard B. Johnson
2001-06-21 20:54 ` Abramo Bagnara
2001-06-21 21:09 ` Oliver Neukum
2001-06-28 22:57 ` Pavel Machek
2001-06-21 13:28 ` Alan Cox
2001-06-21 14:03 ` Matthias Urlichs
2001-06-28 22:54 ` Pavel Machek
2001-06-21 14:20 ` Dmitry A. Fedorov
2001-06-21 11:38 ` Dmitry A. Fedorov
2001-06-21 13:50 ` john slee
2001-06-21 13:58 ` Matthias Urlichs
2001-06-21 14:21 ` john slee
2001-06-28 22:51 ` Pavel Machek
[not found] <mailman.993156181.18994.linux-kernel2news@redhat.com>
2001-06-21 22:06 ` Pete Zaitcev
2001-06-21 22:20 ` David S. Miller
2001-06-21 23:09 ` Mike Mackovitch
2001-06-21 23:22 ` David S. Miller
2001-06-21 23:50 ` Mike Mackovitch
2001-06-22 0:36 ` David S. Miller
2001-06-21 23:40 ` Richard B. Johnson
2001-06-22 0:30 ` Anders Larsen
2001-06-22 0:43 ` Richard B. Johnson
2001-06-25 0:06 ` Anders Larsen
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