Date: Fri, 8 Sep 2017 22:33:12 -0700 From: Russell Haley <russ.haley@gmail.com> To: Warner Losh <imp@bsdimp.com> Cc: "freebsd-arm@freebsd.org" <freebsd-arm@freebsd.org>, "freebsd-arch@freebsd.org" <arch@freebsd.org> Subject: Re: FCP-100: armv7 plan Message-ID: <CABx9NuRVq%2Buuu6yLuzhLU3G3zYZyyLCinXjPQodrpc=Xp-K8uA@mail.gmail.com> In-Reply-To: <CANCZdfqC3xrhSXPQGaf34pGfqrqa9KGXz%2BjLfKTU_O=%2BOKoWXQ@mail.gmail.com> References: <CANCZdfrCwdVOGWunSAjuxHzGcqhuH24iRQg63rvPFXXSmm-C6Q@mail.gmail.com> <CABx9NuSawbewJCD4C72C6dFwQaH3eRxWqBEQokzivJHkdwErQw@mail.gmail.com> <CANCZdfqC3xrhSXPQGaf34pGfqrqa9KGXz%2BjLfKTU_O=%2BOKoWXQ@mail.gmail.com>
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On Fri, Sep 8, 2017 at 10:10 PM, Warner Losh <imp@bsdimp.com> wrote: > > On Fri, Sep 8, 2017 at 7:52 PM, Russell Haley <russ.haley@gmail.com> wrote: >> >> On Fri, Sep 8, 2017 at 4:11 PM, Warner Losh <imp@bsdimp.com> wrote: >> > Greetings, >> > >> > This will serve as 'Last Call' for any objections to the plan to create >> > an >> > armv7 MACHINE_ARCH in FreeBSD, as documented in FCP-0100. >> > >> > Please see https://github.com/freebsd/fcp/blob/master/fcp-0100.md for >> > all >> > the details. This has been discussed in the mailing lists, on IRC, etc >> > and >> > I believe that I've captured the consensus from those discussions. >> > >> > I'm interested in any last minute comments, but as far as I can tell I >> > have >> > consensus on this issue. Absent any comments to the contrary, I'll >> > proceed >> > to having core@ vote that this document represents consensus. Now is the >> > time to speak up if I've gotten anything wrong. >> > >> > Once the core vote is done, I plan on committing the code reviews I have >> > open on this: >> > https://reviews.freebsd.org/D12027 >> > and >> > https://reviews.freebsd.org/D12010 >> > (again, I welcome any commits / criticisms in phabricator on the >> > specific >> > issues in this code) >> > >> > Thanks for any comments... >> > >> > Warner >> > _______________________________________________ >> > freebsd-arm@freebsd.org mailing list >> > https://lists.freebsd.org/mailman/listinfo/freebsd-arm >> > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org" >> >> Hi Warner, >> >> Thanks for your work on this. General thoughts in and around this subject. >> >> 1) I like how you split the commit into generic build system changes >> vs BSP changes. It was helpful in aiding visibility in the code >> changes. > > > Thanks. > >> >> 2) Are these statements true? >> >> - We will not be differentiating hard/soft float. It is assumed >> armv6/7 are hard float (no letter suffixes) > > > Yes. We switched to only hard float on armv6 prior to the switch. While one > can still build a softfloat system, it's not really supported (we don't test > it, we don't build packages for it, etc). That support exists in the tree > for the transition libraries only and may be removed in the future. > >> >> - armv4/5 has no changes > > > Correct. > >> >> - armv6 is split into armv6, armv7 > > > Yes. > >> >> - armv8 is aarch64 > > > armv8 has no (current) meaning to FreeBSD. > >> >> - We will not be supporting aarch64 32 bit extensions for running >> armv6/7 binaries > > > That's an orthogonal problem that a aarch64 kernel will solve, but is > unrelated to the build system. > >> >> - There is no way to run aarch64 on armv7 > > > Nope. > >> >> 3) Can I ask if there will be other armv[0-9+] architectures created >> or do you think everything new will transition to 64 bit? If so, will >> we (FreeBSD) be able to differentiate those architectures in the >> future (aarch64v2)? I guess what I'm asking is "in your expert >> opinion, have we taken enough steps to ensure clean >> code/names/you-get-my-point for future changes?" What else could we >> do? It seems that there is a lot of changes in arm compared to other >> architectures. The rapid development of different things by the Arm >> group and other vendors seems to cause a lot of churn. Do you think >> our naming conventions do enough to take this into consideration? >> Modern hardware manufacturing seem much different then what I am >> reading about in Unix history. Have our naming patterns kept up? > > > Those are all good questions. While it's hard to say for sure they won't be > any new armvX architectures that implement 32-bit ABIs, there's been a > strongly telegraphed signal that all new ARM innovation will be in the > 64-bit area. They've also claimed that new revisions of aarch64 will be more > orderly and less chaotic than things have been in the 32-bit arm world. It's > unclear still if that will actually be the case, but given we have little > basis for guessing the proper names in the future, it's hard to future-proof > here. > >> >> 4) Also, if my supposition about arm 32/64 compatibility is correct, >> do we have plans in place for future boards may have 32/64 bit >> compatibility like the RPi3? Or, is it just two different builds and >> downloads? (which I'm cool with, but would like to know) > > > The notion is that for those AARCH64 SoCs that have the ability to run > 32-bit, we'll have two builds. One will be aarch64 based and the other armv7 > based. We'll likely roll that into armv7 GENERIC so we can get away from > having so many distributions (move to more of a base image + flavoring > step), but that work isn't complete enough to talk much about. > > Work to make RPI3 work with a 32-bit kernel appears to be reaching > completion. There should be something there soon (if it hasn't already been > announced...) > > Warner > > https://www.netgate.com/products/sg-3100.html ? ;) Russ
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