Messages in this thread | | | Date | Fri, 3 Jul 2015 14:40:23 -0700 | Subject | Re: Non-booting current Linus' tree | From | Linus Torvalds <> |
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On Fri, Jul 3, 2015 at 8:23 AM, Jan Kara <jack@suse.cz> wrote: > > Because the address isn't 32-byte aligned (which I assume is the > requirement from looking into the code). So clearly my gcc messed up and > miscompiled the thing by ignoring the alignment attribute.
Well, it's probably a mistake to begin with to expect gcc to get stack alignment right. Especially since we tell gcc to not align the stack as much as it usually wants to with -mpreferred-stack-boundary=2.
The code is broken in other ways too. The fxsave alignment isn't 32 bytes. It's 16 bytes. And that's already encoded in the "struct fxregs_state", so adding that extra alignment is just bogus crud anyway.
So I seriously think that the whole commit 91a8c2a5b43f is just fundamentally broken and should probably be reverted. The theoretical issue it fixes is a smaller problem than the broken code it introduces (and I'm not just talking about gcc bugs).
Plus the code just sets up and writes to a global variable *anyway*, so the alleged race with using a static allocation is bogus: if that's a real concern, then the code is fundamentally buggy in other ways anyway.
I don't think you can boot with different CPU's having different mxcsr features anyway, so..
Ingo?
Linus
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