Date: Sun, 26 Mar 2023 19:35:34 +0100 From: Alexander Chernikov <melifaro@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: Jessica Clarke <jrtc27@freebsd.org>, Ed Maste <emaste@freebsd.org>, src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org Subject: Re: git: a85dcd4ac4b0 - main - netlink: restrict default userland switch to netlink to i386/amd64. Message-ID: <3FCBB04E-F975-42BF-B401-47EAE718FD38@freebsd.org> In-Reply-To: <CANCZdfqKrAiDP359ipUti6yDZ8-xHLw0U3ef27t4GvaC-mBfhw@mail.gmail.com> References: <202303261107.32QB7T7N058867@gitrepo.freebsd.org> <CAPyFy2Bdhi7xWs9-5JzudbVj62GarWeeJ9BwBEK=0smvcT2Dgw@mail.gmail.com> <486C839F-181F-4CE8-8510-4A7D4D100FDC@freebsd.org> <CANCZdfqKrAiDP359ipUti6yDZ8-xHLw0U3ef27t4GvaC-mBfhw@mail.gmail.com>
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> On 26 Mar 2023, at 18:08, Warner Losh <imp@bsdimp.com> wrote: > > > > On Sun, Mar 26, 2023, 6:45 PM Jessica Clarke <jrtc27@freebsd.org> wrote: > On 26 Mar 2023, at 17:17, Ed Maste <emaste@freebsd.org> wrote: >> >> >> On Sun, 26 Mar 2023 at 07:07, Alexander V. Chernikov >> <melifaro@freebsd.org> wrote: >>> >>> The branch main has been updated by melifaro: >>> >>> URL: https://cgit.FreeBSD.org/src/commit/?id=a85dcd4ac4b0612b63b5a71eeaaa707a09ae0003 >>> >>> commit a85dcd4ac4b0612b63b5a71eeaaa707a09ae0003 >>> Author: Alexander V. Chernikov <melifaro@FreeBSD.org> >>> AuthorDate: 2023-03-26 11:05:21 +0000 >>> Commit: Alexander V. Chernikov <melifaro@FreeBSD.org> >>> CommitDate: 2023-03-26 11:06:53 +0000 >>> >>> netlink: restrict default userland switch to netlink to i386/amd64. >> >> We should keep default options the same for all Tier-1 architectures, >> so amd64 and arm64 should be in sync. > > But also, what’s the technical justification for this change? There > should not be gratuitous differences between architectures like this, > only when there is a reason something shouldn’t be enabled. Why should > x86 (and possibly arm64) get netlink, but not arm/powerpc/riscv? We > have very few machine-dependent defaults in src.opts.mk. If there is no > such justification then please revert this in its entirety, and if > there is such a justification it belongs in a comment above the if. > > So if it's a matter of testing, enable it everywhere. We'll get testing. If it's something known to be bad on say riscv64 we should have a bug and reference it in src.opts.mk to document why. If it's just a conservative approach to a roll out, then I'd suggest being less conservative. I’d actually be happy to enable it everywhere and fix the bugs if/when they appear. I’m not sure what is the best way to implement this. Having Netlink on in the userland implies that route(8) (and soon ifconfig(8)) will need kernel-side Netlink support to operate. Thus, for the particular platform, one need to ensure that either (a) Netlink is present in the config or (b) Netlink is loaded as a module during boot. Given that successful boot w/o working route(8) may not just happen, it really boils down to (a). arm (like v6) or ppc or riscv may represent some lower-scale devices, where adding Netlink to the default config may represent a size (or other) concerns [1]. With all that in mind, in order to gather more datapoints & have a gradual conversion, I started with the archs I can reason about. In the end, it’s pretty easy to enable it arch-by-arch (or everywhere) when there is a consensus on the situation mentioned above. [1] https://reviews.freebsd.org/D39047 > > Warner
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