Date: Sat, 28 Jun 2003 10:54:36 -0700 From: Marcel Moolenaar <marcel@xcllnt.net> To: deischen@freebsd.org Cc: threads@freebsd.org Subject: Re: KSE: fuword/suword bugs on ia64 Message-ID: <20030628175436.GA1071@dhcp01.pn.xcllnt.net> In-Reply-To: <Pine.GSO.4.10.10306281150120.8518-100000@pcnet5.pcnet.com> References: <20030628153032.GA577@dhcp01.pn.xcllnt.net> <Pine.GSO.4.10.10306281150120.8518-100000@pcnet5.pcnet.com>
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On Sat, Jun 28, 2003 at 12:20:03PM -0400, Daniel Eischen wrote: > > > > 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? Not really. It's just that I like to be able to defend the size expansion when an alternative exists that does not increase the size. > > 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. Sounds good. Note that on ia64 ucontext_t has 16-byte alignment. Having the fields reordered definitely helps the overall density. BTW: putting tm_context at the end is a good idea. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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