DragonFly kernel List (threaded) for 2005-05
Re: The time has come for a kernel interfacing library layer
On Mon, May 09, 2005 at 09:05:51AM -0700, Matthew Dillon wrote:
> I want to keep the advantage we have with the current system call
> model where we don't mess with errno at all unless the system call
> actually returns an error.
Sure, I want to keep that too. Actually, we have to do that,
since it is the behaviour enforced by POSIX.
> At the moment I do not see a solution better then having the (user level)
> system call layer store errno directly in the tcb. Even a custom
> threading library would have to use our tls_tcb structure, otherwise
> the dynamic linker won't work. So it's not going to be any worse then
> what we already have and the advantage is that the system call layer
> then becomes extremely clean.
We currently don't depend on any TLS mechanism in rtld and
adding such a requirement is a bad thing. Having the shared
memory segment as part of "special" ELF section would solve this,
it could be addressed with the normal PIC mechanism. It could be
placed at a fixed offset in the kernel space and the address given