Linus Torvalds: Intel patches are architectural garbage

When Linus Torvald sees something he doesn't like, he's not afraid to speak his mind. In the past, he hasn't hesitated to call out developers for pulling crap into Linux 4.8, nor was he afraid to tell NVIDIA to go fuck itself. Over the weekend, the Linux founder took a look at some new Linux patches that are related to the Intel CPU bugs and called them "pure garbage".

Slashdot has the meat over here, this is what Linus has to say about the new microcode that addresses Indirect Branch Restricted Speculation "where a future CPU will advertise 'I am able to be not broken' and then you have to set the IBRS bit once at boot time to *ask* it not to be broken:"

Linus calls it "very much part of the whole 'this is complete garbage' issue. The whole IBRS_ALL feature to me very clearly says 'Intel is not serious about this, we'll have a ugly hack that will be so expensive that we don't want to enable it by default, because that would look bad in benchmarks'. So instead they try to push the garbage down to us. And they are doing it entirely wrong, even from a technical standpoint. I'm sure there is some lawyer there who says 'we'll have to go through motions to protect against a lawsuit'. But legal reasons do not make for good technology, or good patches that I should apply."

Later Linus says forcefully that these "complete and utter garbage" patches are being pushed by someone "for unclear reasons" -- and adds another criticism.

The whole point of having cpuid and flags from the microarchitecture is that we can use those to make decisions. But since we already know that the IBRS overhead is huge on existing hardware, all those hardware capability bits are just complete and utter garbage. Nobody sane will use them, since the cost is too damn high. So you end up having to look at "which CPU stepping is this" anyway. I think we need something better than this garbage.