From: Jeff Dike <jdike@karaya.com>
To: Rub n Gallardo Fructuoso <ruben@trymedia.com>
Cc: "Linux-Kernel" <linux-kernel@vger.kernel.org>
Subject: Re: Address translation
Date: Tue, 21 Nov 2000 12:20:48 -0500 [thread overview]
Message-ID: <200011211720.MAA04358@ccure.karaya.com> (raw)
In-Reply-To: Your message of "Tue, 21 Nov 2000 15:41:26 +0100." <DLECJAOCHAKJBLMJFKPIAEPBCCAA.ruben@trymedia.com>
ruben@trymedia.com said:
> Does anybody know a function or method in order to translate an user
> space pointer into a valid pointer in kernel mode?
> I'd like to avoid copying data (such as the 'copy_to_user' and
> 'copy_from_user' functions do) because it slows down my system.
The reason that everyone else uses copy_{to,from}_user is that there is no way
to guarantee that the userspace pointer is valid. That memory may have been
swapped out. The copy macros are prepared to fault the memory in. The rest
of the kernel is not.
Jeff
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next prev parent reply other threads:[~2000-11-21 16:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-21 14:41 Address translation Rubén Gallardo Fructuoso
2000-11-21 17:20 ` Jeff Dike [this message]
2000-11-21 16:32 ` 3c527 driver won't receive packets Egan
2000-11-21 16:36 ` Alan Cox
-- strict thread matches above, loose matches on Subject: below --
2000-11-22 21:39 Address translation Keir Fraser
2000-11-23 0:49 ` Pavel Machek
2000-11-23 20:23 ` Andreas Bombe
2000-11-23 21:04 ` Bjorn Wesen
2000-11-24 23:28 ` Andreas Bombe
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