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Date: Tue, 9 May 2006 23:47:45 -0400 (EDT)
From: Daniel Eischen <deischen@freebsd.org>
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To: David Xu <davidxu@freebsd.org>
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Cc: current@freebsd.org
Subject: Re: Fine-grained locking for POSIX local sockets (UNIX domain
	sockets)
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On Wed, 10 May 2006, David Xu wrote:
> One of the problems to implement it is that atomic operations,
> if there are multiple integer needs to be updated by kernel,
> userland maybe gets an inconsistent result, the way to avoid the
> problem is using two generation numbers.
>
> http://gsu.linux.org.tr/~mpekmezci/kernelapi/unitedlinux/arch/x86_64/kernel/vsyscall.c.html
> check do_vgettimeofday(struct timeval * tv):
>
> Another problem is how you tell userland the address of the kernel
> page ? do you use fixed address or tell it via program headers like
> the PT_TLS set by kernel, check /usr/src/lib/libc/gen/tls.c.

Can you not make a simple pseudo device driver and mmap the page?

-- 
DE