Date: Mon, 11 Oct 1999 09:46:25 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Peter Wemm <peter@netplex.com.au> Cc: Michael Robinson <robinson@netrinsics.com>, freebsd-alpha@freebsd.org Subject: Re: How 64-bit is Alpha FreeBSD? Message-ID: <Pine.BSF.4.10.9910110945310.91778-100000@salmon.nlsystems.com> In-Reply-To: <19991011061043.1FBDC1CCE@overcee.netplex.com.au>
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On Mon, 11 Oct 1999, Peter Wemm wrote: > Michael Robinson wrote: > > Doug Rabson <dfr@nlsystems.com> 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
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