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Date:   Thu, 23 Nov 2023 17:33:31 +0000
From:   "Jiaxun Yang" <jiaxun.yang@flygoat.com>
To:     "Thomas Bogendoerfer" <tsbogend@alpha.franken.de>
Cc:     "Serge Semin" <fancer.lancer@gmail.com>,
        "Arnd Bergmann" <arnd@arndb.de>,
        "Andrew Morton" <akpm@linux-foundation.org>,
        "Mike Rapoport" <rppt@kernel.org>,
        "Matthew Wilcox" <willy@infradead.org>,
        "Tiezhu Yang" <yangtiezhu@loongson.cn>,
        "Huacai Chen" <chenhuacai@kernel.org>,
        "Yinglu Yang" <yangyinglu@loongson.cn>,
        "Alexey Malahov" <Alexey.Malahov@baikalelectronics.ru>,
        "Aleksandar Rikalo" <aleksandar.rikalo@syrmia.com>,
        "Aleksandar Rikalo" <arikalo@gmail.com>,
        "Dragan Mladjenovic" <dragan.mladjenovic@syrmia.com>,
        "Chao-ying Fu" <cfu@wavecomp.com>, "Marc Zyngier" <maz@kernel.org>,
        "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/7] mips: dmi: Fix early remap on MIPS32
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=E5=9C=A82023=E5=B9=B411=E6=9C=8823=E6=97=A5=E5=8D=81=E4=B8=80=E6=9C=88 =
=E4=B8=8B=E5=8D=884:07=EF=BC=8CThomas Bogendoerfer=E5=86=99=E9=81=93=EF=BC=9A
> On Thu, Nov 23, 2023 at 03:07:09PM +0000, Jiaxun Yang wrote:
>>=20
[...]
>
> the problem with all 32bit unmapped segments is their limitations in
> size. But there is always room to try to use unmapped and fall back
> to mapped, if it doesn't work. But I doubt anybody is going to
> implement that.

Yep, I guess fallback should be implemented for ioremap_cache as well.

>
>> >> AFAIK for Loongson DMI is located at cached memory so using iorema=
p_uc
>> >> blindly will cause inconsistency.
>> >
>> > why ?
>>=20
>> Firmware sometimes does not flush those tables from cache back to mem=
ory.
>> For Loongson systems (as well as most MTI systems) cache is enabled by
>> firmware.
>
> kernel flushes all caches on startup, so there shouldn't be a problem.

Actually dmi_setup() is called before cpu_cache_init().

Thanks
>
> Thomas.
>
> --=20
> Crap can work. Given enough thrust pigs will fly, but it's not necessa=
rily a
> good idea.                                                [ RFC1925, 2=
.3 ]

--=20
- Jiaxun