From owner-freebsd-alpha Mon Oct 11 1:47: 5 1999 Delivered-To: freebsd-alpha@freebsd.org Received: from herring.nlsystems.com (nlsys.demon.co.uk [158.152.125.33]) by hub.freebsd.org (Postfix) with ESMTP id E6DAA14D32 for ; Mon, 11 Oct 1999 01:47:01 -0700 (PDT) (envelope-from dfr@nlsystems.com) Received: from salmon.nlsystems.com (salmon.nlsystems.com [10.0.0.3]) by herring.nlsystems.com (8.9.3/8.8.8) with ESMTP id JAA20563; Mon, 11 Oct 1999 09:46:25 +0100 (BST) (envelope-from dfr@nlsystems.com) Date: Mon, 11 Oct 1999 09:46:25 +0100 (BST) From: Doug Rabson To: Peter Wemm Cc: Michael Robinson , freebsd-alpha@freebsd.org Subject: Re: How 64-bit is Alpha FreeBSD? In-Reply-To: <19991011061043.1FBDC1CCE@overcee.netplex.com.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, 11 Oct 1999, Peter Wemm wrote: > Michael Robinson wrote: > > Doug Rabson writes: > > >We support a 42 bit user address space right now. This is a hardware > > >limitation for older alphas but could be changed for newer hardware which > > >could probably extend it to 55 bits. > > > > Thanks. > > > > Does that mean, theoretically speaking, that if I were running FreeBSD on an > > Alpha with sufficient kernel memory, and 2 terabytes of data files, I could > > mmap the whole 2 terabytes into one process? > > I'm pretty sure the FreeBSD VM system is limited to 1TB - ie: 512 bytes > times 2^31 - to enable use of native types rather than synthetic 64 bit > types in the kernel in performance critical areas. I'm not sure how this > relates to the Alpha though since it has 'long' == 64 bit and it might be > 512 x 2^63. I'm pretty sure I've seen int32_t types instead of 'long' so I > wouldn't count on it. I haven't checked for int32 types in the VM code but the machdep code uses mostly int64 types. The largest address space I have tried is about 12G. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message