Comment 101 for bug 1835660

@Siarhei

That looks very valid. And we were close to getting to that, when apw & I timed out looking at this.

lz4 -l Use Legacy format (typically for Linux Kernel compression)
              Note : -l is not compatible with -m (--multiple) nor -r

Which must always be used when creating initrd. Ideally, both userspace output and linux kernel consumption should agree what said legacy format should look like and what it must produce and consume.

Is https://github.com/lz4/lz4/blob/dev/doc/lz4_Frame_format.md#legacy-frame underspecified, or does lz4 produce non-compliant frames, or kernel misprocesses compliant frames?

Also, can we upgrade lz4 in the kernel tree to 1.9.2?