Re: KIP and other user mappings

On Tue Dec 12, 2006 at 23:06:04 +0000, bahadir balban wrote:
>Hi,
>
>In L4, what offsets and pages does the userspace need to know about by 
>standard?
>
>On ARM (NICTA::Pistachio hello 1.1) for instance, KernelInterface() is
>entered via a trap at offset 0xFFFFFFb4, and there are other traps
>nearby. Does the userspace need to know about these by standard or are
>they there for convenience? My expectation would be that it would only
>need to know a fixed offset for KernelInterface() call.

User land also needs to know the range of virtual address space available
which is available through the KIP.

>Also, are there other pages than the KIP that the userland expects to
>find? For instance, USER_UTCB_REF is defined at 0xFF000FF0
>(l4/include/arm/vregs.h), almost at the end of the KIP page for ARM.
>Is it part of the KIP? Does the userspace need to know it's offset in
>advance, or is it to be discovered from the KIP?

Userspace knows about this through the L4 library. So from that point of
view, yes userspace knows about that in advance. It is not discovered
through the KIP.

Cheers,

Benno