Re: [PATCH v3 0/6] Composefs: an opportunistically sharing verified image filesystem

From: Alexander Larsson
Date: Mon Feb 06 2023 - 10:36:09 EST


On Mon, Feb 6, 2023 at 2:27 PM Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote:
> On 2023/2/6 20:43, Alexander Larsson wrote:
> >
> > One problem I ran into is that erofs seems to only support mounting
> > filesystem images that are created with the native page size. This
> > means I can't mount a erofs image created on a 4k page-size machine on
> > an arm64 mac with 64k pages. That doesn't seem great. Maybe this
> > limitation can be lifted from the erofs code though.
>
> Honestly, EROFS 64k support has been in our roadmap for a quite long
> time, and it has been almost done for the uncompressed part apart from
> replacing EROFS_BLKSIZ to erofs_blksiz(sb).

Good, as long as it is on the roadmap.

> Currently it's not urgent just because our Cloud environment always use
> 4k PAGE_SIZE, but it seems Android will consider 16k pagesize as well, so
> yes, we will support !4k page size for the uncompressed part in the near
> future. But it seems that arm64 RHEL 9 switched back to 4k page size?

Honestly I'm not following it all that closely, but I think Fedora was
at least talking about 64k pages.

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Alexander Larsson Red Hat, Inc
alexl@xxxxxxxxxx alexander.larsson@xxxxxxxxx