Subject: Re: Sample splice(2) via kcont(9), work-in-progress towards sendfile()
To: Jonathan Stone <>
From: Chuck Silvers <>
List: tech-kern
Date: 10/06/2005 08:45:19
On Wed, Oct 05, 2005 at 11:00:11AM -0700, Jonathan Stone wrote:
> Anyone object if I and reserve these two ssycall numbers,
> as UNIMPL for now?


(I think you already implied this in earlier mail, but just in case...)

we should really discuss the syscall API before anything is committed
(including allocating any syscall numbers).

the splice() API as proposed isn't very flexible at all, I would say
that it should be enhanced to the point that sendfile() can just be
a wrapper around splice() and not need to be a syscall itself.
(that's why even allocating syscall numbers is premature, if we don't
agree on how many.)
also, I'd think that splice() should be able to work with any kind of file
descriptor that can be read from with read() or written to with write().
some kind of uio-like structure seems in order.

... actually I just looked at how sendfile() was defined in other OSs,
and apparently it's different on different platforms.  so given that,
it doesn't buy us much to have a separate sendfile() function at all.
ideally splice() would be able to implement any of those sendfile() APIs,