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Date:      Tue, 4 Nov 2014 06:23:34 -0800
From:      Alfred Perlstein <bright@mu.org>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, Alfred Perlstein <alfred@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, Mateusz Guzik <mjg@FreeBSD.org>
Subject:   Re: svn commit: r274017 - head/sys/kern
Message-ID:  <E513A7CD-FA5C-4BC2-ACA1-03370948ECE9@mu.org>
In-Reply-To: <88CC9FA2-D677-484A-8D6B-9DA66D8479AE@mu.org>
References:  <201411030746.sA37kpPu037113@svn.freebsd.org> <5457F771.3010509@freebsd.org> <20141104092558.GP53947@kib.kiev.ua> <88CC9FA2-D677-484A-8D6B-9DA66D8479AE@mu.org>

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> On Nov 4, 2014, at 6:22 AM, Alfred Perlstein <bright@mu.org> wrote:
> 
> 
> 
>>> On Nov 4, 2014, at 1:25 AM, Konstantin Belousov <kostikbel@gmail.com> wrote:
>>> 
>>> On Mon, Nov 03, 2014 at 01:45:21PM -0800, Alfred Perlstein wrote:
>>> Isn't there a problem where the stack can be swapped out?
>>> 
>>> I seem to recall a problem where a swapped out process was causing 
>>> problems due to a buffer passed being stack allocated and that process 
>>> being swapped out...
>>> 
>>> If this is not the case then please disregard.
>> 
>> Sure, stack can be swapped out, but buffer passing is usually not a problem.
>> At least, I am not aware of cases.
>> 
>> In fact, many compat layers do exactly this, allocate the native-ABI
>> structure on the stack, copyin the foreighn-ABI structure in pieces
>> into the native-ABI one, and pass native to kern_foo() implementations.
>> 
>> So I think you worries are not realized.
> 
> Ok then as long as system will not pass this buffer as Dma target down to driver we are ok.  

Also thank you for explanation. 

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