MIME-Version: 1.0
References: <20230308064734.512457-1-suagrfillet@gmail.com> <20230308113510.fb6y2xhylavkrgtl@bogus>
In-Reply-To: <20230308113510.fb6y2xhylavkrgtl@bogus>
From:   Song Shuai <suagrfillet@gmail.com>
Date:   Thu, 9 Mar 2023 07:54:45 +0000
Message-ID: <CAAYs2=jFe_ejN9O26AMCZqDtnVkt1bpyMUw2nx1Q9t=SBWj79A@mail.gmail.com>
Subject: Re: [PATCH] Revert "riscv: Set more data to cacheinfo"
To:     Sudeep Holla <sudeep.holla@arm.com>, conor.dooley@microchip.com
Cc:     paul.walmsley@sifive.com, palmer@dabbelt.com,
        aou@eecs.berkeley.edu, pierre.gondois@arm.com,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Hi, Conor & Sudeep :

Sudeep Holla <sudeep.holla@arm.com> =E4=BA=8E2023=E5=B9=B43=E6=9C=888=E6=97=
=A5=E5=91=A8=E4=B8=89 11:35=E5=86=99=E9=81=93=EF=BC=9A
>
> On Wed, Mar 08, 2023 at 02:47:34PM +0800, Song Shuai wrote:
> > This reverts commit baf7cbd94b5688f167443a2cc3dcea3300132099.
> >
> > There are some duplicate cache attributes populations executed
> > in both ci_leaf_init() and later cache_setup_properties().
> >
> > Revert the commit baf7cbd94b56 ("riscv: Set more data to cacheinfo")
> > to setup only the level and type attributes at this early place.
> >
>
> I had noticed the same and had something similar when we did some rework
> around for v6.1 merge window. But there were lot of other issues to be
> addressed at the moment and hence deferred this.
>
> So for the change in general, but as Conor responded, it would be good
> to do some checking to ensure nothing breaks and all the requirements
> this patch(baf7cbd94b56) addressed are already handled in the core.

As you suggested, commit (da29dbcda49d "riscv: Add cache information
in AUX vector")
in the "Get cache information from userland" series should be checked.

The commit da29dbcda49d adds the cacheinfo (read from
ci_cacheinfo(cpu)) in ELF auxiliary vectors,
so process can fetch the cacheinfo through glibc sysconf() after ELF loadin=
g.
At the same time, the glibc related support was enabled by its commit
(15b38ffc10 "riscv: Get cache information through sysconf")

With this reverting patch applied, the output of `getconf -a` looks good
in Qemu sifive_u machine and rootfs image with glibc-2.35.

```
LEVEL1_ICACHE_SIZE 32768
LEVEL1_ICACHE_ASSOC 8
LEVEL1_ICACHE_LINESIZE 64
LEVEL1_DCACHE_SIZE 32768
LEVEL1_DCACHE_ASSOC 8
LEVEL1_DCACHE_LINESIZE 64
LEVEL2_CACHE_SIZE 2097152
LEVEL2_CACHE_ASSOC 32
LEVEL2_CACHE_LINESIZE 64
```

>
> Acked-by: Sudeep Holla <sudeep.holla@arm.com>
>
> --
> Regards,
> Sudeep


--=20
Thanks,
Song