Make ZSTD optional via options ZSTDIO.

[sbruno]

Summary

It looks like the intent was to allow ZSTD support to be
compiled into the kernel with options ZSTDIO. But it doesn't look
like that was ever implemented or I'm missing how to do it.

[markj]

Doesn't it also need to be conditional on ZFS support?

[sbruno]

In D16007#338847, @markj wrote:

Doesn't it also need to be conditional on ZFS support?

Yeah, I'm not sure TBH. I didn't want to blindly fire this into the tree without someone who knows what this stuff does give it some thought.

[cem]

This could be fine. Does everything else still compile? I'd make sure the kernel dump compression DTRT w/ the option off and ZFS too. I don't know of any other kernel consumers.

[sbruno]

In D16007#338847, @markj wrote:

Doesn't it also need to be conditional on ZFS support?

Maybe I just don't see it. What's the relationship between ZFS and ZSTD?

http://facebook.github.io/zstd/

[cem]

In D16007#338919, @sbruno wrote:

Maybe I just don't see it. What's the relationship between ZFS and ZSTD?

ZFS supports compressing file data. One algorithm it can use is Zstd.

Edit: https://reviews.freebsd.org/D11124 — I guess it's not in OpenZFS nor FreeBSD yet.

[sbruno]

In D16007#338923, @cem wrote:

In D16007#338919, @sbruno wrote:

Maybe I just don't see it. What's the relationship between ZFS and ZSTD?

ZFS supports compressing file data. One algorithm it can use is Zstd.

Edit: https://reviews.freebsd.org/D11124 — I guess it's not in OpenZFS nor FreeBSD yet.

Ah, ok. I did ye olde "grep -ri zstd" to see if I could test this. Didn't return any results and I thought I was daft.

[cem]

In D16007#338924, @sbruno wrote:

In D16007#338923, @cem wrote:

Edit: https://reviews.freebsd.org/D11124 — I guess it's not in OpenZFS nor FreeBSD yet.

Ah, ok. I did ye olde "grep -ri zstd" to see if I could test this. Didn't return any results and I thought I was daft.

Ya, mea culpa. I think you are good from the ZFS side for now; it'll be up to Allan to use the option/macro.

[allanjude]

I'll update the zstd-zfs patch to deal with this once it lands, it shouldn't be an issue.

[sbruno]

Add riscv and mips configurations to keep ZSTDIO building for
the GENERIC target and MALTA targets (std.MALTA).