From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Qu Wenruo <quwenruo.btrfs@gmx.com>, Neal Gompa <ngompa13@gmail.com>
Cc:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linuxppc-dev@lists.ozlabs.org,
        Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
        linux-hexagon@vger.kernel.org, Hector Martin <marcan@marcan.st>
Subject: Re: [PATCH] fs: btrfs: Disable BTRFS on platforms having 256K pages
In-Reply-To: <db88497c-ea17-27ca-6158-2a987acb7a1c@gmx.com>
References: <a16c31f3caf448dda5d9315e056585b6fafc22c5.1623302442.git.christophe.leroy@csgroup.eu>
 <6c7a6762-6bec-842b-70b4-4a53297687d1@gmx.com>
 <CAEg-Je9UJDJ=hvLLqQDsHijWnxh1Z1CwaLKCFm+-bLTfCFingg@mail.gmail.com>
 <db88497c-ea17-27ca-6158-2a987acb7a1c@gmx.com>
Date:   Fri, 07 Jan 2022 15:55:51 +1100
Message-ID: <87bl0o2lgo.fsf@mpe.ellerman.id.au>
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Qu Wenruo <quwenruo.btrfs@gmx.com> writes:
> On 2022/1/7 00:31, Neal Gompa wrote:
>> On Wed, Jan 5, 2022 at 7:05 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>>
>>> Hi Christophe,
>>>
>>> I'm recently enhancing the subpage support for btrfs, and my current
>>> branch should solve the problem for btrfs to support larger page sizes.
>>>
>>> But unfortunately my current test environment can only provide page size
>>> with 64K or 4K, no 16K or 128K/256K support.
>>>
>>> Mind to test my new branch on 128K page size systems?
>>> (256K page size support is still lacking though, which will be addressed
>>> in the future)
>>>
>>> https://github.com/adam900710/linux/tree/metadata_subpage_switch
>>>
>>
>> The Linux Asahi folks have a 16K page environment (M1 Macs)...
>
> Su Yue kindly helped me testing 16K page size, and it's pretty OK there.
>
> So I'm not that concerned.
>
> It's 128K page size that I'm a little concerned, and I have not machine
> supporting that large page size to do the test.

Did Christophe say he had a 128K system to test on?

In mainline powerpc only supports 4K/16K/64K/256K.

AFAIK there's no arch with 128K page size support, but that's only based
on some grepping, maybe it's hidden somewhere.

cheers