Re: git: 2a58b312b62f - main - zfs: merge openzfs/zfs@431083f75 [separate aarch64 panic for zpool import]

On 4/8/23, Kyle Evans <kevans@freebsd.org> wrote:
> On Fri, Apr 7, 2023 at 4:54 PM Mateusz Guzik <mjguzik@gmail.com> wrote:
>>
>> On 4/7/23, Mark Millard <marklmi@yahoo.com> wrote:
>> > On Apr 7, 2023, at 14:26, Mateusz Guzik <mjguzik@gmail.com> wrote:
>> >
>> >> On 4/7/23, Mateusz Guzik <mjguzik@gmail.com> wrote:
>> >>> can you try with this:
>> >>>
>> >>> diff --git
>> >>> a/sys/contrib/openzfs/include/os/linux/kernel/linux/simd_aarch64.h
>> >>> b/sys/contrib/openzfs/include/os/linux/kernel/linux/simd_aarch64.h
>> >>> index 16276b08c759..e1bca9ef140a 100644
>> >>> ---
>> >>> a/sys/contrib/openzfs/include/os/linux/kernel/linux/simd_aarch64.h
>> >>> +++
>> >>> b/sys/contrib/openzfs/include/os/linux/kernel/linux/simd_aarch64.h
>> >>> @@ -71,7 +71,7 @@
>> >>> #define        ID_AA64PFR0_EL1         sys_reg(3, 0, 0, 1, 0)
>> >>> #define        ID_AA64ISAR0_EL1        sys_reg(3, 0, 0, 6, 0)
>> >>>
>> >>> -#define        kfpu_allowed()          1
>> >>> +#define        kfpu_allowed()          0
>> >>> #define        kfpu_begin()            kernel_neon_begin()
>> >>> #define        kfpu_end()              kernel_neon_end()
>> >>> #define        kfpu_init()             (0)
>> >>>
>> >>>
>> >>
>> >> ops, wrong file
>> >>
>> >> diff --git a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_arm.h
>> >> b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_arm.h
>> >> index 178fbc3b3c6e..c462220289d6 100644
>> >> --- a/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_arm.h
>> >> +++ b/sys/contrib/openzfs/include/os/freebsd/spl/sys/simd_arm.h
>> >> @@ -46,7 +46,7 @@
>> >> #include <machine/elf.h>
>> >> #include <machine/md_var.h>
>> >>
>> >> -#define        kfpu_allowed()          1
>> >> +#define        kfpu_allowed()          0
>> >> #define        kfpu_initialize(tsk)    do {} while (0)
>> >> #define        kfpu_begin()            do {} while (0)
>> >> #define        kfpu_end()              do {} while (0)
>> >
>> > It will take me a bit to setup a separate build/install
>> > context for the source code vintage involved. Then more
>> > time to do the build, install, and test. (I'm keeping
>> > my normal environments completely before the mess.)
>> >
>> > FYI:
>> >
>> > I have used the artifact build just after your pair of zfs
>> > related updates to confirm the VFP problem is still in
>> > place as of that point:
>> >
>> > https://artifact.ci.freebsd.org/snapshot/main/5e2e3615d91f9c0c688987915ff5c8de23c22bde/arm64/aarch64/kernel.txz
>> >
>> > (No artifact build was exactly at either of your commits.)
>> >
>> > ===
>> > Mark Millard
>> > marklmi at yahoo.com
>> >
>> >
>>
>> I have arm64 + zfs at $job and just verified the above lets it boot
>> again, so I committed already.
>>
>
> This was a known issue that we were working on fixing properly over in
> https://reviews.freebsd.org/D39448... this really could have waited
> just a little bit longer. This problem was already brought up in
> response to the commit in question days ago.
>

Mate, that's one confusing email.

I had seen the upstream review, apparently there is opposition to the
patch, it is clearly not going to land within hours.

Whatever the Real Fix(tm) might be, I'm confident my change has no
impact on work on it, past the need to flip kfpu_allowed back to 1.

At the same time things were broken to the point where aarch64 + zfs
literally did not boot. Once more, I fail to see how restoring basic
operation by fipping a macro to 0 throws any wrenches into the effort
to get simd working.

If anything the question is how come a clearly *not* implemented simd
support got kfpu_allowed set to 1.

-- 
Mateusz Guzik <mjguzik gmail.com>