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From: Robert Watson <rwatson@FreeBSD.org>
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To: Daniel Eischen <deischen@freebsd.org>
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Cc: MingyanGuo <guomingyan@gmail.com>, delphij@gmail.com,
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Subject: Re: Why use `thread' as an argument of Syscalls?
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On Mon, 5 Jun 2006, Daniel Eischen wrote:

>> They are the same questions, I think ;-). Now would you please explain "why 
>> use `proc' as an argument of Syscalls"  to me :)?  I've read some source 
>> code of the kernel, but no comments about it found.
>
> I don't know.  Convention?  It makes sense to me.

Certainly consistency.  Most system calls do actually use the argument at some 
point -- be it to look up a file descriptor, access control, or the like, and 
the calling context has it for free and in-hand anyway.

Robert N M Watson