Re: [linus:master] BUILD REGRESSION a2e5790d841658485d642196dbb0927303d6c22f

[Peter Zijlstra]

On Wed, Feb 07, 2018 at 11:03:42AM -0800, Linus Torvalds wrote:
> On Wed, Feb 7, 2018 at 10:49 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > Right, we picked UD0 because we _thought_ everybody agreed it being 2
> > bytes, just like UD2. This is now not true anymore?
> 
> Both UD0 and UD1 are documented to have modrm in the latest Intel SDM
> I can find (Order number 325462-065US, December 2017):

Thanks, and yes :/ They changed it in October17 (which I actually had a copy
of so I'm not sure why I was looking at March17).

Back when we did that patch the SDM didn't have that extra ModR/M on,
and binutils disassembled it as the 2 byte (bad) thing, which was all
good.

Then someone went and wrecked it.