From owner-freebsd-arch Tue Nov 21 19:14:32 2000 Delivered-To: freebsd-arch@freebsd.org Received: from pcnet1.pcnet.com (pcnet1.pcnet.com [204.213.232.3]) by hub.freebsd.org (Postfix) with ESMTP id 8988337B4D7; Tue, 21 Nov 2000 19:14:29 -0800 (PST) Received: (from eischen@localhost) by pcnet1.pcnet.com (8.8.7/PCNet) id WAA27090; Tue, 21 Nov 2000 22:14:09 -0500 (EST) Date: Tue, 21 Nov 2000 22:14:09 -0500 (EST) From: Daniel Eischen To: John Baldwin Cc: Jonathan Lemon , arch@FreeBSD.org Subject: Re: Thread-specific data and KSEs In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 21 Nov 2000, John Baldwin wrote: > On 22-Nov-00 Daniel Eischen wrote: > > On Tue, 21 Nov 2000, John Baldwin wrote: > >> > >> On 22-Nov-00 Daniel Eischen wrote: > >> > Why can't we use a segment register? > >> > >> %cs = code segment and is taken > >> %ds = data segment and is taken > >> %es = not sure, but bet it isn't safe > >> %ss = stack, taken > >> %fs = per-CPU data > > > > Isn't this kernel-only? > > I think so, but I would prefer that we use %gs if we go this route so that the > same mechanism can be used both in and out of the kernel. If that makes sense. That's fine with me. > >> %gs ? as I mentioned in my other message, this one might be useful for > >> addressing a structure of thread-local variables much like %fs is used for > >> per-CPU data. It also has value in that supposedly x86-64 (aka k64) has > >> both > >> %fs and %gs, but no other seg regs. > > > > All I need is one. > > Well, %gs would cover x86 and k64. I think ia64 has several application > registers that are available for OS use and we could steal one of those. I'm > not sure about the alpha though. OK, I think we can use an S register. These are suppose to be call-safe, if I can believe sys/alpha/include/asm.h. Any alpha gurus care to respond? -- "Some folks are into open source, but me, I'm into open bar." -- Spencer F. Katt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message