On Linus’ Return to Kernel Development

On October 23, 2018, Linus Torvalds came out of his self-imposed isolation, pulling a lot of patches from the git trees of various developers. It was his first appearance on the Linux Kernel Mailing List since September 16, 2018, when he announced he would take a break from kernel development to address his sometimes harsh behavior toward developers. On the 23rd, he announced his return, which I cover here after summarizing some of his pull activities.

For most of his pulls, he just replied with an email that said, "pulled". But in one of them, he noticed that Ingo Molnar had some issues with his email, in particular that Ingo's mail client used the iso-8859-1 character set instead of the more usual UTF-8. Linus said, "using iso-8859-1 instead of utf-8 in this day and age is just all kinds of odd. It looks like it was all fine, but if Mutt has an option to just send as utf-8, I encourage everybody to just use that and try to just have utf-8 everywhere. We've had too many silly issues when people mix locales etc and some point in the chain gets it wrong."

On the 24th, Linus continued pulling from developer trees. One of these was a batch of networking updates from David Miller, and it included contributions from a lot of different people. Linus noticed that the Kconfig rules were running into unmet dependency warnings because the code expected to run on the Qualcomm architecture, which Linus didn't use. He suggested it was a simple matter of updating the dependency list in the code. He also asked why the developers didn't notice that problem when testing their patches. Kalle Valo explained, "Mostly bad timing due to my vacation. I did do allmodconfig build but not sure why I missed the warning, also the kbuild bot didn't report anything. Jeff did report it last week, but I was on vacation at the time and just came back yesterday and didn't have time to react to it yet."

That seemed fine to Linus, who said he'd pull the fix when it became available. He remarked, "I just don't want my tree to have warnings that I see, and that may hide new warnings coming in when I do my next pull request."

On the 25th, Linus continued pulling from developer trees. In one instance, the issue of minimal tool versions came up. Linus prefers to support as many regular users as possible, which means supporting tool versions from the Linux distributions.

In response to a hard-to-read patch, Andi Kleen suggested changing the minimum supported binutils version from 2.20 to 2.21, which would support some useful assembler opcodes that would make the patch easier to review. Andy Lutomirski, another of the patch reviewers, said this would be fine. And Linus said: