[Buildroot] [PATCH 2/2] Adding btrfs rootfs option.

[Yann E. MORIN <yann.morin.1998@free.fr>]

Robert, All,

On 2018-08-22 18:57 +0200, Yann E. MORIN spake thusly:
> On 2018-08-22 14:10 +0100, Robert Heywood spake thusly:
> > On 21/08/18 21:27, Yann E. MORIN wrote:
[--SNIP--]
> > >Given that the filsystem is specifically made for the target that will
> > >mount it, does it make sense to ffer that option at all? I.e. if the
> > >target uses a 4KiB page size, does it make sense to generatea rootfs
> > >that has a different secotr size, and thus not mountable on the target
> > >at all?
> > >
> > >My suggestion: don't add that option.
> > 
> > On my system (building for a raspi0) it autodetects the sector size to be
> > 4k, and the resulting image is bootable. However I'm worried the host won't
> > be able to detect the correct value for the target. In such a case I can see
> > why it would be useful to set the sector size explicitly.
> 
> Well, basically all architectures have a 4K page size, so does your
> x86_64 and so does the rpi (0/1/2/3), so the default for your host is
> valid for your target.
> 
> What architectures have a page-size that is not 4K?

After discussing on IRC with Paul (Cc), it turns out that quite a few
architectures can have a page size different from 4K, like mips, arc and
a few others. Sometimes it is even configrable. Thanks Paul.

4K just happens to be the most common, but definitely not the only one.

> > Is there another place where the sector size is specified? If so, it might
> > be better to use the existing value instead.
> I would also add a default here, to 4096. Users who want to change
> that value would know what they would be doing.

So yeah, just keep that option, and let set the default to 4K. People
who have a non 4K arch or kernel option will know to change that value.

Regards,
Yann E. MORIN.

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