KSE: fuword/suword bugs on ia64

[Daniel Eischen]

On Sat, 28 Jun 2003, Marcel Moolenaar wrote:
> On Sat, Jun 28, 2003 at 10:06:02AM -0400, Daniel Eischen wrote:
> > > 
> > > I've started runtime testing and ran into ILP32/LP64 bugs. Attached
> > > a patch that solve the first problems without affecting i386. The
> > > patch is intended to illustrate the problem more than it suggest a
> > > solution. I'm more than happy to test alternative solutions.
> > > Note that the use of uint32_t instead of unsigned int is mostly
> > > to mirror the use of fuword32/suword32...
> > 
> > I don't have any problem with the patch.  Is there another
> > solution you'd rather see, perhaps using 64bit values?
> 
> I was thinking about using long. fuword/suword is defined in terms
> of long, so technically it's a bug to have them operate on int. But
> using long will yield 64-bit fields on 64-bit platforms, and it may
> just be a waste of space. Although internal alignment and padding
> may already take up as much space (tm_flags, km_version, km_flags
> are examples of this).

The mailboxes are not that big (with the exception of the
thread mailbox due to ucontext), so a few extra bytes isn't
going to hurt userland.  Perhaps the copyin/copyout's in
the kernel is what you're worried about?

> I'm divided on the issue. I prefer using long for it being the best
> native type, but don't like the immediate consequence of it being
> too variable for use in interface types (take for example the 64-bit
> long on i386 that bde is playing with). With the patch I favored
> the fixed width property on uint32_t.

You can use uint32_t for now as a quick fix.  Perhaps
we should restructure the mailboxen a bit as a longer
term fix.  David just added siginfo to the thread
mailbox, so that's another MD structure. 

	struct kse_thr_mailbox {
		/* u_long		tm_version; */ /* ??? */
		struct kse_thr_mailbox	*tm_next;
		void			*tm_udata;
		uint32_t		tm_flags;
		uint32_t		tm_uticks;
		uint32_t		tm_sticks;
		uint32_t		tm_spare[9];
		siginfo_t		tm_syncsig;
		ucontext_t		tm_context;
	}

This allows tm_context to change without affecting offsets
to the other fields.  The KSE mailbox has a version in it
which can also identify what version of the thread mailbox,
but it might make sense to stick a version field in the
thread mailbox to make things easier.

-- 
Dan Eischen