Date: Tue, 13 Jun 2000 08:29:51 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Daniel Eischen <eischen@vigrid.com> Cc: Bruce Evans <bde@zeta.org.au>, arch@FreeBSD.ORG Subject: Re: Syscalls and execve Message-ID: <Pine.BSF.4.21.0006130826530.68954-100000@salmon.nlsystems.com> In-Reply-To: <Pine.SUN.3.91.1000610083735.5916A-100000@pcnet1.pcnet.com>
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On Sat, 10 Jun 2000, Daniel Eischen wrote:
> On Sat, 10 Jun 2000, Doug Rabson wrote:
> > The trapframe which is created for syscall is identical to the trapframe
> > for exceptions and interrupts, its just not fully populated with register
> > values.
>
> On a related subject, the alpha sigcontext is different than the
> trapframe. This makes implementing {get,set}context slightly more
> difficult because they have to know which frame is in the machine
> context. For the new threads architecture (similar to scheduler
> activations), the context of threads that become unblocked in
> the kernel is passed out to the user threads library. I want to
> add {get,set}context as library routines and use them to handle
> both signal contexts and trapframes as passed out of the kernel.
>
> This isn't a big deal, we can just have a different set of routines
> to handle trapframes for the alpha, but if there is an opportunity
> to make trapframes and signal frames consistent (as they are on
> i386)...
It would be difficult to make trapframe match sigcontext without changing
sigcontext to look more like the current trapframe (which is partly
dictated by PALcode). I don't think the associated cost of changing the
kernel ABI is worth the gain. Also, the fpregs state is totally unneeded
for trapframe since the kernel doesn't disturb the fp state during traps.
--
Doug Rabson Mail: dfr@nlsystems.com
Nonlinear Systems Ltd. Phone: +44 20 8442 9037
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