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Date:      Tue, 18 Apr 2023 23:52:09 +0100
From:      Jessica Clarke <jrtc27@freebsd.org>
To:        Warner Losh <imp@bsdimp.com>
Cc:        Warner Losh <imp@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>" <dev-commits-src-main@freebsd.org>
Subject:   Re: git: 238271f4a66b - main - stand: Add a snarky note about the upstream ZFS situation
Message-ID:  <B84E9112-427A-4B93-940A-A7734D00A3AB@freebsd.org>
In-Reply-To: <CANCZdfry1T-xy-xQ19Cch42qmeNNAHFgQf_W61FCbSHWis_aNg@mail.gmail.com>
References:  <202304182131.33ILVSoG020217@gitrepo.freebsd.org> <C898F70B-7CA2-451F-A080-ADBFB472561D@freebsd.org> <CANCZdfry1T-xy-xQ19Cch42qmeNNAHFgQf_W61FCbSHWis_aNg@mail.gmail.com>

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On 18 Apr 2023, at 23:49, Warner Losh <imp@bsdimp.com> wrote:
>=20
>=20
>=20
> On Tue, Apr 18, 2023, 3:34 PM Jessica Clarke <jrtc27@freebsd.org> =
wrote:
>> On 18 Apr 2023, at 22:31, Warner Losh <imp@FreeBSD.org> wrote:
>> >=20
>> > The branch main has been updated by imp:
>> >=20
>> > URL: =
https://cgit.FreeBSD.org/src/commit/?id=3D238271f4a66bd06b8b9a232a82f3ee08=
82e4cbb9
>> >=20
>> > commit 238271f4a66bd06b8b9a232a82f3ee0882e4cbb9
>> > Author:     Warner Losh <imp@FreeBSD.org>
>> > AuthorDate: 2023-04-18 21:29:45 +0000
>> > Commit:     Warner Losh <imp@FreeBSD.org>
>> > CommitDate: 2023-04-18 21:31:17 +0000
>> >=20
>> >    stand: Add a snarky note about the upstream ZFS situation
>> >=20
>> >    The latest import of openzfs broke the hacks that we used to =
omit the
>> >    special registers being used on arm64. Add snarky note =
documenting this
>> >    situation since it's a mess now since the hack was only =
partially
>> >    undone, leaving behind a mess.
>> >=20
>> >    Sponsored by:           Netflix
>> > ---
>> > stand/libsa/zfs/Makefile.inc | 4 ++++
>> > 1 file changed, 4 insertions(+)
>> >=20
>> > diff --git a/stand/libsa/zfs/Makefile.inc =
b/stand/libsa/zfs/Makefile.inc
>> > index f4cecdbc3085..7660f4ab7baf 100644
>> > --- a/stand/libsa/zfs/Makefile.inc
>> > +++ b/stand/libsa/zfs/Makefile.inc
>> > @@ -19,6 +19,7 @@ ZSTD_SRC+=3D  zstd_common.c
>> > ZSTD_SRC+=3D    zstd_ddict.c zstd_decompress.c =
zstd_decompress_block.c
>> > ZSTD_SRC+=3D    zstd_double_fast.c zstd_fast.c zstd_lazy.c =
zstd_ldm.c
>> >=20
>> > +# This is completely bogus: We should be able to omit this code =
completely.
>> > .if ${MACHINE_ARCH} =3D=3D "aarch64"
>> > ZFS_SRC_AS =3D  b3_aarch64_sse2.S b3_aarch64_sse41.S
>> > .endif
>> > @@ -90,10 +91,13 @@ CFLAGS.skein_block.c+=3D    -DSKEIN_LOOP=3D111
>> >=20
>> > # To find blake3_impl.c in OpenZFS tree for our somehat ugly =
blake3_impl_hack.c
>> > # that's needed until the necessary tweaks can be upstreamed.
>> > +# XXX the last import gutted all this since upstream changes broke =
this hack.
>> > CFLAGS.blake3_impl_hack.c+=3D -I${OZFS}/module/icp/algs/blake3 =
-I${OZFS}/module/icp/include
>> >=20
>> > CWARNFLAGS.zfs.c+=3D ${NO_WDANGLING_POINTER}
>> >=20
>> > +# Needing to remove the -mgeneral-regs-only is a red flag that =
this is not quite
>> > +# right. But it's needed at the moment due to the muddled =
upstream.
>>=20
>> This one isn=E2=80=99t bogus? The file is deliberately using NEON so =
needs
>> access to floating-point registers, which LLVM (mostly) enforces for
>> the assembler, unlike GNU as.
>=20
> No. It's bogus because we should not be using it at all. The generic =
implementation is fast enough for the boot loader and we have a blanket =
policy against using extra register sets. The change wasn't discussed =
before hand and what's really needed are upstream changes to be able to =
omit it entirely.

Oh I see, I misunderstood the point the comment was making.

Thanks,
Jess

> > b3_aarch64_sse2.o: b3_aarch64_sse2.S
> >       ${CC} -c ${CFLAGS:N-mgeneral-regs-only} ${WERROR} ${.IMPSRC} \
> >           -o ${.TARGET}




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