Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: anton@mips.complang.tuwien.ac.at (Anton Ertl) Newsgroups: comp.arch Subject: Re: x86S Specification Date: Tue, 22 Oct 2024 15:26:20 GMT Organization: Institut fuer Computersprachen, Technische Universitaet Wien Lines: 30 Message-ID: <2024Oct22.172620@mips.complang.tuwien.ac.at> References: <3c6510cc947a1b59b62753de4cf98293@www.novabbs.org> Injection-Date: Tue, 22 Oct 2024 17:53:34 +0200 (CEST) Injection-Info: dont-email.me; posting-host="f278bba9e5b934d8e2784ee170fcc373"; logging-data="1627397"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19B+f3V7FYCSc1K9lqnf3oQ" Cancel-Lock: sha1:UBQB4FPxDaDPH3JUM72mz0QhilE= X-newsreader: xrn 10.11 Bytes: 2498 John Levine writes: >Think about the way that current Intel chips have a native 64 bit architecture >but can still have a 32 bit user mode that can run existing 32 bit application >binaries. So how about if the next generation is native x86S, but can also run >existing 64 bit binaries, even if not as fast as native x86S. They get the usual >cloud operating systems ported to x86S while leaving a path for people to migrate >their existing applications gradually. Several things in this paragraph makes no sense. In particular, x86S is a proposal for a reduced version of the stuff that current Intel and AMD CPUs support: There is full 64-bit support, and 32-bit user-level support. x86S eliminates a part of the compatibility path from systems of yesteryear, but not that many people use these parts nowadays anyway. It's unclear to me what benefits these changes are supposed to buy (unlike the elimination of A32/T32 from some ARM chips, which obviously eliminates the whole A32/T32 decoding path). It seems to me that most of the complexity of current CPUs would still be there. And I certainly prefer a CPU that has more capabilities to one that has less capabilities. Sometimes I want to run old binaries. So what would be my incentive as a user to buy an x86S CPU? Will they sell them for less? I doubt it. - anton -- 'Anyone trying for "industrial quality" ISA should avoid undefined behavior.' Mitch Alsup,