That again is very subjective view, David. Sorry. Arm32 is kinda kind of the hill these days in the low-power/low cost space, but arm as a company is much more interested it seems in going into server / mobile device space rather than solidifying it's current de-facto kingdom. Those platforms based on their IP are very short lived and tightly coupled to a particular vendor with zillions busses, various kinds of weird quirks, vendor-maintained bootloaders etc. On the other hand, Intel is quickly closing the gap. If you've seen any of the atom bay trail systems in action you may understand what I mean. You get full blown x64 system with four cores and it takes only 2W of power. This is roughly equivalent of ARM8 system with a single core @ only 900MHz.
So my prediction is in the 32-bit land arm will fade out as a platform and be replaced with RiscV in matter of few years and i386 will probably continue to be the platform of choice for many if Intel/Amd play that card right. -Max On Fri, May 25, 2018, 12:27 AM David Chisnall <thera...@freebsd.org> wrote: > On 25 May 2018, at 05:27, Maxim Sobolev <sobo...@freebsd.org> wrote: > > > > The idea looks very inmature and short-sighted to me. i386 is here to > stay not as a server/desktop platform but as an embedded/low power/low cost > platform for at least 5-10 years to come. There are plenty of applications > in the world that don't need > 3gb of memory space and have no use for > extra bits (and extra silicon) to function. > > This argument seems very odd to me. If you are targeting the embedded > space, it is far easier to build a low-power chip that targets the x86-64 > ISA than the x86-32 ISA. You can move all of the 80-bit floating point > stuff into microcode. You can put anything using pair-of-32-bit-register > 64-bit operations into slow microcode. You can skimp on store forwarding > for stack addresses. You actually need fewer rename registers (one of the > biggest consumers of power), because x86-64 code needs to do less register > juggling to fit in the architectural register space. All of these things > are big consumers of power and area and are far less necessary when running > code compiled for x86-64. You can also do tricks like the one that Intel > did on the early Atoms, where the SSE ALUs are actually only 64 bits wide > and the 128-bit ops are cracked into pairs of 64-bit micro-ops. > > As to ‘not needing more than 3GB of memory space’, that’s what the x32 ABI > is for. This lets you get all of the advantages of the x86-64 ISA (of > which there are very many, in comparison to x86-32), without needing 64-bit > pointers. You get the instruction density of x86-64 combined with the data > density of x86-32. This is what Intel and Centaur have been pushing in the > embedded space for several years. > > You do pay a slight hardware cost from supporting a 48-bit virtual address > space, though with superpages that’s negligible and the hardware targeted > at these applications often doesn’t support more than a 32-bit virtual > address space. > > And this completely ignores the fact that Intel has almost no presence in > the low-end embedded space. AArch32 is vastly more important there and if > we dropped x86-32 and shifted that effort to AArch32 then I think we’d see > a lot more adoption. > > David > _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
