Messages in this thread | | | From | Linus Torvalds <> | Date | Sat, 22 Aug 2020 14:08:27 -0700 | Subject | Re: [PATCH] x86: work around clang IAS bug referencing __force_order |
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On Sat, Aug 22, 2020 at 11:17 AM Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> wrote: > > However, the important question is whether those users/companies care > about running the latest kernels. Many of those definitely do not want > to touch their kernel either. For those that do, there are several > longterms to pick from that still support 4.9, as well as other > workarounds. > > Thus I am usually in favor of raising the minimum whenever new hacks > are required to be added. On the other hand, we already raised the > version twice this year and it is not clear to me what is the minimum > version we would need to go for to ensure this does not bite us.
Yeah. The good news is that I haven't seen a lot of pushback on the gcc version updates so far. I was expecting some complaints. I haven't seen a single one.
That may be because people did end up finding it very onerous and complained internally on channels I haven't seen, but it might also be indicative of us having perhaps been a bit too timid about compiler version updates.
However, in this case, can we just leave that old "__force_order" hack alone, and to work around the clang thing, just make a dummy definition of it anyway.
Alternatively, just use the memory clobber. We use memory clobbers elsewhere in inline asms to make sure they are serialized, it's not normally a huge problem. Both clang and gcc should be smart enough to know that a memory clobber doesn't matter for things like local variables etc that might be on stack but have never had their address taken.
Or are there other cases than that particular __force_order thing that people now worry about?
Linus
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