What You Need To Know About Linux

So says none aside from Linus Torvalds himself, in his Linux Kernel Mailing List post declaring the first release candidate of Linux 4.9.

Torvalds chucked in a barb with that post, by releasing it on a Saturday day and explaining why as follows:

“I usually do the releases on a Sunday afternoon, but sometimes cut the merge window short by a day only to keep people on their toes, and make sure people learn to not send in last-minute pull requests. This is one particular release.”

Torvalds says this will be a traditional release, with lots of bugs to be fixed. But he also called out two new accessions.

“The big new thing is the greybus improvement, which Greg swears is actually becoming used.” “Greg” is kernel developer Greg Kroah-Hartman and “greybus” is this part of Project Ara. As Kroah-Hartman posted last monht, “Greybus is an hardware protocol that has been designed to provide Unipro with a sane application layer. It was originally designed for the ARA project, a module phone system, but has shown up in other phones, and can be tunneled over other busses to be able to control hardware devices.”

So maybe Google’s vision is not entirely dead.

Torvalds says his favourite addition is “Andy Lutomirski’s new essentially mapped kernel stack allocations” because “They make it easier to locate and recover from stack overflows, but the effort also cleaned up some code, and added a kernel stack mapping cache to prevent any operation drawbacks.”

“The virtual stack mapping also happens to mean that people who try to do DMA from temporary buffers on the stack (‘Don’t do it!’) now actually need to change their bad ways. So there is some fallout from this, and I expect a few drivers to desire small fixes. But it’s all for a good cause, actually (and it isn’t all that common, because doing DMA from the stack actually has never been a great notion, and is usually not even workable in most situations).”