Date: Tue, 29 Jul 1997 19:30:39 -0700 From: David Greenman <dg@root.com> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Location of copyin() and copyout().. Message-ID: <199707300230.TAA11782@implode.root.com> In-Reply-To: Your message of "Wed, 30 Jul 1997 11:47:21 %2B0930." <199707300217.LAA16641@genesis.atrad.adelaide.edu.au>
next in thread | previous in thread | raw e-mail | index | archive | help
>David Greenman stands accused of saying: >> >> There is no problem with using copyout() in the kernel to copy data out to >> a user process, assuming that the currently running process is the intended >> target of the copy. That is the sole purpose of the function. copyout() >> correctly handles all issues of COW/ZF/page faults. > >The only issue here is that the consumer of your service may _not_ be >a user process, eg. in the case of an ABI emulation module. I would >specifically request that people avoid using copyout unless they can >be _absolutely_ certain that they will only ever be talking to user >processes. > >As I said, this has already caused me heartache several times 8( I don't understand the distinction you're making. copyout *always* runs in the (kernel) context of a user process and the destination is always process (as opposed to kernel) memory. Please explain. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199707300230.TAA11782>