Re: [PATCH] sched/x86: Save [ER]FLAGS on context switch
From: Linus Torvalds
Date: Fri Feb 15 2019 - 19:22:10 EST
On Fri, Feb 15, 2019 at 3:34 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> Now, EFLAGS bit 1 is supposedly always 1, but it really doesn't seem to
> matter for POPF.
Correct, it's "read as 1", you can try to write it and it doesn't matter.
> I went through the other flags, and aside from VIP/VIF (I've no clue),
> they looks like 0 should be just fine.
So 0 is a perfectly valid initializer in the sense that it _works_, I
just want it to be something that was thought about, not just a random
"initialize to zero" without thinking.
Even just a comment about it would be fine. But it might also be good
to show that it's an explicit eflags value and just use
X86_EFLAGS_FIXED as the initializer.