Date: Wed, 10 Jan 2018 16:49:29 -0800 From: Alex Zepeda <mips@inferiorhumanorgans.com> To: freebsd-mips@freebsd.org Subject: Re: Switch to hard-float by default? Message-ID: <20180111004929.GA17499@bloaty> In-Reply-To: <CANCZdfp=82mpjO3C3L_RXrPa66nouFfgpKxtzezxoe1S2RzCzQ@mail.gmail.com>
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> On Wed, Jan 10, 2018 at 12:54 PM, John Baldwin <jhb@freebsd.org> wrote: > > > I have been working on LLVM libunwind patches for MIPS and the last round > > has > > been to teach the unwinder to handle hard-float. As part of this I just > > fixed > > a bug which had broken HF support for N32 (in review now), and I have a > > working 'mipsn32hf' world that boots under qemu. However, if I add > > 'mipsn32hf' to the list of known targets that is yet another world to add > > to make universe. I wonder if instead we should consider switching MIPS to > > assume hard-float by default? We made that change for 32-bit arm recently. > > > > The simplest approach would be to add 'mipsn32hf' and then remove all the > > non '*hf' targets from Makefile.inc1 (if we only wanted to support HF). A > > more drastic approach would be to change the existing 'mips*' targets to > > assume hard-float, remove all the '*hf' targets (which are only in 12 > > anyway > > I think?) and add in explicit '*sf' targets if anyone has a need for them. > > Given that none of the *hf targets have been MFC'd are only present in 12 > > anyway, maybe the more drastic route is actually better? If we do go that > > route, does anyone have a use case for a '*sf' target? That is, is anyone > > running FreeBSD/mips on a processor that does not include an FPA? > > > > I think that I retired the last set of SoCs that only had soft float. > > I think this is a good idea. > > The only use case I can think of is if I'm wrong and some of the early > Atheros SoCs can do soft float. But then we'd just have one supported > soft-float platform to worry about rather than the full generality we have > now. > > Warner Are you sure? I'm pretty sure a lot of the 32 bit SoCs don't have FPUs standard. I'm currently poking at a MediaTek 7621 board (EdgeRouter X) and it doesn't have an FPU. Looking through the MediaTek documents it looks like FPUs are an optional accessory on many of their SoCs. AZhome | help
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