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Message-ID: <9083c414-62f2-4bff-93ee-13f8ff60eb34@linaro.org>
Date: Wed, 21 Feb 2024 16:38:06 +0100
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Subject: Re: [PATCH v2] arm64: defconfig: Enable zram, xfs and loading
 compressed FW support
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To: Maxime Ripard <mripard@redhat.com>
Cc: Javier Martinez Canillas <javierm@redhat.com>,
 linux-kernel@vger.kernel.org, Enric Balletbo i Serra <eballetbo@redhat.com>,
 Erico Nunes <nunes.erico@gmail.com>, Brian Masney <bmasney@redhat.com>,
 Arnd Bergmann <arnd@arndb.de>, Bjorn Andersson <quic_bjorande@quicinc.com>,
 Catalin Marinas <catalin.marinas@arm.com>,
 Geert Uytterhoeven <geert+renesas@glider.be>,
 Konrad Dybcio <konrad.dybcio@linaro.org>,
 Marek Szyprowski <m.szyprowski@samsung.com>,
 Neil Armstrong <neil.armstrong@linaro.org>, Will Deacon <will@kernel.org>,
 linux-arm-kernel@lists.infradead.org
References: <20240221141350.3740488-1-javierm@redhat.com>
 <1f28256c-e436-4add-aa67-2cfb2248b220@linaro.org>
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 <fy3wffb2jwv4veo3golfn5olri77clxywbuwuokese7sbobixd@mird5k66cl2w>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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On 21/02/2024 16:24, Maxime Ripard wrote:
> On Wed, Feb 21, 2024 at 04:10:12PM +0100, Krzysztof Kozlowski wrote:
>> On 21/02/2024 15:48, Maxime Ripard wrote:
>>> On Wed, Feb 21, 2024 at 03:22:38PM +0100, Krzysztof Kozlowski wrote:
>>>> On 21/02/2024 15:13, Javier Martinez Canillas wrote:
>>>>> These options are needed by some Linux distributions (e.g: Fedora), so
>>>>
>>>> How ZRAM is needed? Why Fedora cannot boot without it? Debian, which I
>>>> use on my arm64 boards, does not have any problem.
>>>
>>> Is it relevant in any way?
>>
>> Yes, because it is justification why we are doing it. Each commit is
>> supposed to explain "why" and the explanation here is not enough.
> 
> There's a why though: it makes Fedora boot. It might not be enough for

I want to know to understand. Maybe it is not really neeed but "nice to
have"? People write various vague statements...

> you, but that's a different story. So, if it's not enough, please state
> exactly what you expect from that patch description so Javier can
> provide it.

Any explanation what ZRAM is necessary for Fedora to boot.

> 
>>> I'm sure Debian can boot without MEMORY_HOTREMOVE, or BRIDGE, or
>>> NUMA_BALANCING, or BPF_JIT, or NFS_FS, yet all of them are enabled. Let
>>> me know if you want hundreds more examples.
>>
>> So if there is any bug, you are allowed to add new one? If there is any
>> silly option, you are allowed to add new one?
>>
>> Feel free to propose dropping of any irrelevant options.
> 
> No, of course you aren't. My point is that Fedora is a distro just as
> established and legitimate as Debian is. And apparently "it makes Debian
> works" is a reasonable argument, since, well, it does.
> 
> If making Fedora boot with that defconfig is not a legitimate goal,

It is, but I asked for more information.

> please state why, and document it (with the ack of all the maintainers
> involved with that defconfig, obviously) so we don't have the same
> argument over and over again.
> 
>>>> I kind of repeat comments from similar patch earlier:
>>>> https://lore.kernel.org/all/fe1e74a2-e933-7cd9-f740-86d871076191@linaro.org/
>>>>
>>>> About XFS: I don't think it is needed to boot anything.
>>>
>>> Just like 9P_FS, NFS or UBIFS.
>>
>> NFS is often used on targets, e.g. my board farm, but also by other people.
>>
>> UBIFS was added recently because one device was using it - you needed
>> it. 9P_FS looks unnecessary.
> 
> So all we need is one person or use case to require it? Sounds like
> we've checked that mark here.

Use case of given type. I would disagree for SMBFS because we have NFS.
UBIFS is hardware requirement. 9P_FS seems like virtio case.

> 
>>>> This is a defconfig, not a distro config. Please don't make it distro.
>>>>
>>>> I will gladly support things needed by systemd or equivalent, but not
>>>> unusual filesystems needed by distro.
>>>
>>> It's a defconfig. It's whatever people want it to be. Or we need to come
>>> up with a clearly defined set of rules of what is acceptable in that
>>> defconfig or not, and prune every option that isn't.
>>
>> So that's the rule I am commenting from time to time. defconfigs are not
>> distro configs. These are reference hardware configs and debugging
>> configs.
> 
> Supporting a board farm is hardly either.

Debugging purpose, but I agree we can drop it.

> 
> And again, I've never heard of such rule for that defconfig in my ~10y
> as an ARM platform maintainer. But what do I know, right?
> 
>> I was working in distro so trust me - they do stuff differently
>> and they not need XFS in our defconfig for anything.
> 
> Sure, but you're not just arguing for XFS there.

I raised need for "why" for ZRAM and un-necessity of XFS. What's wrong
with that? I should send separate emails or what?

> 
> What I really don't get is this: this makes the life of people easier.

Again: this makes my life harder. I cannot be buying new machines every
two years to be able to compile defconfig while testing/working.

> 
> Being able to test an upstream kernel quickly when you have a bug in a
> downstream distro is super valuable for any distro developper. And on

That's a distro need, not relevant. And even if it was, then your
argument would be "let's enable everything distro has!". This is not a
distro kernel.


> the long run, if we don't make the switch from a kernel distro to a
> mainline kernel relatively easy, we're the ones that will lose out.
> Because people just won't bother, or be frustrated and thus super
> reluctant to do that work.
> 
> That's the part I don't get. Why do we want to make the life of people
> harder. This patch has never been about making the defconfig the main

Because it makes my life harder and I don't see benefits. Quoting Arnd:
"Unfortunately this will increase build time noticeably, but"

Best regards,
Krzysztof