Linus Torvalds just released Linux 5.19-rc7 following a busy week due to the Retbleed security mitigation and not only the CPU overhead performance impact it puts on users but the mess it has on kernel development especially when it comes to embargoed issues that make the patches difficult to review/test well prior to embargo lift.
Beyond Retbleed requiring changes to many files and being one of the larger mitigations in recent times, there was some fallout with compiler warnings and other build issues coming up. With Linux 5.19-rc7 it looks like the initial Retbleed mitigation code is all in good shape and should be happily running on affected processors.
Linux upstream development was also made more difficult this week with the Intel Alder Lake P “GuC” firmware regression I called out this week and will now end up either being fixed or reverted for v5.19. Right now a patch is pending to provide backwards compatibility with the older firmware otherwise Linus will revert the GuC v70 support if necessary.
Linux 5.19-rc7 also marks the new Intel IFS driver as “broken” until its sysfs interface is deemed solid.
And then just the usual assortment of bug fixes. Needless to say, Linus Torvalds noted today that the Linux 5.19 cycle will be drawn out an extra week. So expect Linux 5.19-rc8 next Sunday rather than any final release. Linux 5.19 stable in turn should be out in two weeks.
It was a rough week in Linux kernel land. As Linus wrote, when it rains, it pours.
Below is Linus Torvalds’ 5.19-rc7 announcement:
Another week, another rc. We obviously had that whole “Retbleed” thing, and it does show up in both the diffstat and the shortlog, and rc7 is definitely bigger than usual.
And also as usual, when we’ve had one of those embargoed [hardware] issues pending, the patches didn’t get the open development, and then as a result missed all the usual sanity checking by all the automation build and test infrastructure we have. So no surprise – there’s been various small fixup patches afterwards too for some corner cases.
That said, last week there were two other development trees that independently also asked for an extension, so 5.19 will be one of those releases that have an additional rc8 next weekend before the final release. We had some last-minute btrfs reverts, and there’s also a pending issue with a intel GPU firmware.
When it rains it pours.
Not that things really look all that bad. I think we’ve got the retbleed fallout all handled (knock wood), and the btrfs reverts are in place. And the Intel GPU firmware issue seems to have a patch pending too (or we’ll just revert). So it’s not like we have any huge issues, but an extra week is most definitely called for.
At least when Linux 5.19 is out on 31 July, there are many new features with this kernel.