On that Spectre mitigations discussion

Post Syndicated from corbet original https://lwn.net/Articles/745111/rss

By now, almost everybody has probably seen the press coverage of Linus Torvalds’s remarks about one of the
patches addressing Spectre variant 2. Less noted, but much more
informative, is David Woodhouse’s response
on why those patches are the way they are. “That’s why my initial
idea, as implemented in this RFC patchset, was to stick with IBRS on
Skylake, and use retpoline everywhere else. I’ll give you ‘garbage
patches’, but they weren’t being ‘just mindlessly sent around’. If we’re
going to drop IBRS support and accept the caveats, then let’s do it as a
conscious decision having seen what it would look like, not just drop it
quietly because poor Davey is too scared that Linus might shout at him
again.