Date: Mon, 18 Nov 2024 09:49:15 -0700 From: Warner Losh <imp@bsdimp.com> To: Brooks Davis <brooks@freebsd.org> Cc: Ed Maste <emaste@freebsd.org>, src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 4ef07eb0802a - main - getentropy: Add Git hashes corresponding to SVN references Message-ID: <CANCZdfpAjLL_gaLFWaL_n8SbJTjJ4W2sPDKLW3xZZep%2B9qtq1A@mail.gmail.com> In-Reply-To: <ZztqO9XIDej2RhUl@spindle.one-eyed-alien.net> References: <202411161523.4AGFNBcu010436@gitrepo.freebsd.org> <ZztqO9XIDej2RhUl@spindle.one-eyed-alien.net>
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--0000000000001096b0062732b387 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Nov 18, 2024 at 9:24=E2=80=AFAM Brooks Davis <brooks@freebsd.org> w= rote: > On Sat, Nov 16, 2024 at 03:23:11PM +0000, Ed Maste wrote: > > The branch main has been updated by emaste: > > > > URL: > https://cgit.FreeBSD.org/src/commit/?id=3D4ef07eb0802a6353faf79d58719d800= 8decabae0 > > > > commit 4ef07eb0802a6353faf79d58719d8008decabae0 > > Author: Ed Maste <emaste@FreeBSD.org> > > AuthorDate: 2024-11-16 15:18:16 +0000 > > Commit: Ed Maste <emaste@FreeBSD.org> > > CommitDate: 2024-11-16 15:22:46 +0000 > > > > getentropy: Add Git hashes corresponding to SVN references > > > > getentropy has a comment about a special case to support kernels > between > > SVN revisions r331280 and r337999. Add the corresponding Git hashe= s > so > > there's a usable reference after Subversion infrastructure > disappears. > > This code should likely be removed soon as the fix commit is in 12.0.0. > It's not completely clear cut as it is post ino64 and thus not > completely in the "can't possibably work" category. > So we can just delete it. This code is for running newly compiled binaries with kernels that are in a 4 month window in 2018. This is 'forwar= d compat' code. Generally, we don't provide forward compatibility code, except when it affects the upgrade for a "short" window or other very well defined exceptions. One could quibble over the exact bounds of this purposely fuzzy rule, but this is so far outside those bounds that we can just delete this code. As brooks points out, there's dozens of new system calls since then that are also used, in addition to the ino64 changes, that have no 'forward compat code'. In the past, we've said we officially we don't support forward compat at all, though had the softer line due to the difficulty in rollback. But BE's likely will make the 'no forward compat' more often, rather than less, since the kernel and user space can trivially be rolled back. The 'fuzzy' rules developed in a UFS-only world which required greater care and efforts to not brick systems. It might be a good thing for srcmgr to document the policy to provide better guidance than the current tribal knowledge we need. Warner --0000000000001096b0062732b387 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">= <div dir=3D"ltr" class=3D"gmail_attr">On Mon, Nov 18, 2024 at 9:24=E2=80=AF= AM Brooks Davis <<a href=3D"mailto:brooks@freebsd.org">brooks@freebsd.or= g</a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin= :0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"= >On Sat, Nov 16, 2024 at 03:23:11PM +0000, Ed Maste wrote:<br> > The branch main has been updated by emaste:<br> > <br> > URL: <a href=3D"https://cgit.FreeBSD.org/src/commit/?id=3D4ef07eb0802a= 6353faf79d58719d8008decabae0" rel=3D"noreferrer" target=3D"_blank">https://= cgit.FreeBSD.org/src/commit/?id=3D4ef07eb0802a6353faf79d58719d8008decabae0<= /a><br> > <br> > commit 4ef07eb0802a6353faf79d58719d8008decabae0<br> > Author:=C2=A0 =C2=A0 =C2=A0Ed Maste <emaste@FreeBSD.org><br> > AuthorDate: 2024-11-16 15:18:16 +0000<br> > Commit:=C2=A0 =C2=A0 =C2=A0Ed Maste <emaste@FreeBSD.org><br> > CommitDate: 2024-11-16 15:22:46 +0000<br> > <br> >=C2=A0 =C2=A0 =C2=A0getentropy: Add Git hashes corresponding to SVN ref= erences<br> >=C2=A0 =C2=A0 =C2=A0<br> >=C2=A0 =C2=A0 =C2=A0getentropy has a comment about a special case to su= pport kernels between<br> >=C2=A0 =C2=A0 =C2=A0SVN revisions r331280 and r337999.=C2=A0 Add the co= rresponding Git hashes so<br> >=C2=A0 =C2=A0 =C2=A0there's a usable reference after Subversion inf= rastructure disappears.<br> <br> This code should likely be removed soon as the fix commit is in 12.0.0.<br> It's not completely clear cut as it is post ino64 and thus not<br> completely in the "can't possibably work" category.<br></bloc= kquote><div><br></div><div>So we can just delete it. This code is for runni= ng newly compiled</div><div>binaries with kernels that are in a 4 month win= dow in 2018. This is 'forward</div><div>compat' code. Generally, we= don't provide forward compatibility code,</div><div>except when it aff= ects the upgrade for a "short" window or other very well</div><di= v>defined exceptions. One could quibble over the exact bounds of this</div>= <div>purposely fuzzy rule, but this is so far outside those bounds that we<= /div><div>can just delete this code. As brooks points out, there's doze= ns of new</div><div>system calls since then that are also used, in addition= to the ino64 changes,</div><div>that have no 'forward compat code'= . In the past, we've said we officially</div><div>we don't support = forward compat at all, though had the softer line due</div><div>to the diff= iculty in rollback. But BE's likely will make the 'no forward compa= t'</div><div>more often, rather than less, since the kernel and user sp= ace can trivially</div><div>be rolled back. The 'fuzzy' rules devel= oped in a UFS-only world which</div><div>required greater care and efforts = to not brick systems.</div><div><br></div><div>It might be a good thing for= srcmgr to document the policy to provide</div><div>better guidance than th= e current tribal knowledge we need.</div><div><br></div><div>Warner</div></= div></div> --0000000000001096b0062732b387--
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