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From: Pavel Machek <pavel@ucw.cz>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: vojtech@ucw.cz, Alan Cox <alan@lxorguk.ukuu.org.uk>,
	"J.E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	john stultz <johnstul@us.ibm.com>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: Voyager subarchitecture for 2.5.46
Date: Sun, 10 Nov 2002 20:18:23 +0100	[thread overview]
Message-ID: <20021110191822.GA1237@elf.ucw.cz> (raw)
In-Reply-To: <Pine.LNX.4.44.0211101050170.9581-100000@home.transmeta.com>

Hi!

> > Unfortunately, this means "bye bye vsyscalls for gettimeofday".
> 
> Not necessarily. All of the fastpatch and the checking can be done by the
> vsyscall, and if the vsyscall notices that there is a backwards jump
> in

I believe you need to *store* last value given to userland. Checking
backwards jump can be dealt with, but to check for time going
backwards you need to *store* result each result of vsyscall. I do not
think that can be done from userlnad.

> That said, I suspect that the real issue with vsyscalls is that they don't
> really make much sense. The only system call we've ever found that matters
> at all is gettimeofday(), and the vsyscall implementation there looks like
> a "cool idea, but doesn't really matter (and complicates things a lot)".

I don't like vsyscalls at all...
									Pavel
-- 
When do you have heart between your knees?

  reply	other threads:[~2002-11-10 19:13 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-11-05 20:45 Voyager subarchitecture for 2.5.46 J.E.J. Bottomley
2002-11-06  2:31 ` john stultz
2002-11-06 13:43   ` Alan Cox
2002-11-06 21:35     ` john stultz
2002-11-06 15:03   ` J.E.J. Bottomley
2002-11-06 15:38     ` Alan Cox
2002-11-06 16:09       ` Christer Weinigel
2002-11-06 15:45     ` Linus Torvalds
2002-11-06 16:19       ` Alan Cox
2002-11-06 16:12         ` Linus Torvalds
2002-11-06 16:45           ` Alan Cox
2002-11-10 16:30           ` Pavel Machek
2002-11-10 18:59             ` Linus Torvalds
2002-11-10 19:18               ` Pavel Machek [this message]
2002-11-10 19:31                 ` Linus Torvalds
2002-11-10 19:42                   ` Pavel Machek
2002-11-10 19:48                     ` Vojtech Pavlik
2002-11-10 20:02                     ` Sean Neakums
2002-11-10 20:16                       ` Lars Marowsky-Bree
2002-11-10 22:11                         ` Alan Cox
2002-11-10 19:46               ` Vojtech Pavlik
2002-11-11 20:40                 ` john stultz
2002-11-11 20:57                   ` J.E.J. Bottomley
2002-11-11 21:36                     ` William Lee Irwin III
2002-11-11 21:58                     ` john stultz
2002-11-11 22:49                       ` J.E.J. Bottomley
2002-11-11 23:12                         ` john stultz
2002-11-12 12:16                     ` Pavel Machek
2002-11-11 22:08                   ` Vojtech Pavlik
2002-11-06 20:07       ` john stultz
2002-11-06 22:36       ` H. Peter Anvin
2002-11-06 19:30     ` john stultz

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