From: Jeff Dike <jdike@addtoit.com>
To: Young Koh <young.koh@gmail.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] copy_from_user in SKAS mode
Date: Tue, 17 May 2005 21:18:27 -0400 [thread overview]
Message-ID: <20050518011827.GA13287@ccure.user-mode-linux.org> (raw)
In-Reply-To: <3524bf1f0505171633edddc7@mail.gmail.com>
On Tue, May 17, 2005 at 07:33:26PM -0400, Young Koh wrote:
> i'm trying to understand how copy_from_user (and copy_to_user) is
> working in SKAS mode. i started from copy_from_user_skas, and followed
> the functions. but i kinda got lost and couldn't get the intuition how
> data are transferred to the UML kernel, which is a different process.
> Could anyone explain how copy_from_user works in SKAS mode? i'd really
> appreciate it. Thank you!
Since UML has no direct access to the process userspace (i.e. process
virtual addresses are meaningless in the kernel), it has to translate
them to physical addresses. So, each page containing a piece of the
incoming buffer is translated into a physical page, and the data copied
from there.
Jeff
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next prev parent reply other threads:[~2005-05-18 1:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-17 23:33 [uml-devel] copy_from_user in SKAS mode Young Koh
2005-05-18 1:18 ` Jeff Dike [this message]
2005-05-18 13:47 ` Young Koh
2005-05-18 15:08 ` Jeff Dike
2005-05-18 22:34 ` Young Koh
2005-05-19 13:41 ` Blaisorblade
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