[PATCH v2 1/2] lib: zstd: update to latest Linux zstd 1.5.2

[Maier, Brandon L Collins]

Hi Tom

> On Fri, Jan 06, 2023 at 11:26:36PM +0000, Maier, Brandon L:
> > > From: Tom Rini <trini at konsulko.com>
> > > It's all not ideal, yes, but it looks like BTRFS is the main user, right now, which
> > > isn't widely enabled. So maybe we can look towards improving upstream a
> > > bit here, if motivated.
> >
> > I can't speak for the BTRFS code as I don't have a suitable platform
> > to test it on. But the zstd code does appear to be broken on master.
> > Running the zstd compression test in sandbox or sandbox64 both
> > segfault. And I have similar problems trying to decompress FIT images
> > on our AARCH64 platform. The primary motivation to this patch is that
> > the new version does work. And this seems like the appropriate fix
> > given Linux has abandoned the original version of this code.
> 
> Well, I guess in the end, non-functional smaller code is factually worse
> than larger functional code, so, I'll pick this up post v2023.01,
> thanks!

I did some deeper investigation and discovered a bunch of functions were being inlined that caused about 3k of growth. As well as a BMI2 feature that can be disabled to save about 800B on x86 platforms. With those it brings the code size change to about -3k for arm64, and +1k for arm. I'll send a v4 patch series shortly.

> 
> --
> Tom