svn commit: r215178 - in head: lib/libc/sys sys/kern sys/sys

Ivan Voras ivoras at freebsd.org
Tue Nov 16 00:34:35 UTC 2010


On 15 November 2010 18:10, Luigi Rizzo <rizzo at iet.unipi.it> wrote:

> 2. [generic] passing pointers between userland and kernel
> requires remapping the pointer when going up or down.
> As the mapping would be application specific, i don't
> see much use in allowing room for a pointer without kernel code
> to map userland <-> kernel pointers.

I'm not thinking of passing a *working* pointer into the kernel but
used as a cookie, similar to how it's used in kqueue: the intention
being the application can send and get a pointer which means something
to the application, not something usable to the kernel.

Without using intptr_t, if an application wants to hang a structure on
the cookie, it needs to maintain its own translation table
(index-to-pointer).


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