Re: [PATCH 0/2] x86: Use "er" asm constriant for add/sub

Re: [PATCH 0/2] x86: Use "er" asm constriant for add/sub

[Jonathan Cameron]

On Sun, 23 Aug 2026 23:35:36 +0100
Jonathan Cameron <jonathan.cameron@oss.qualcomm.com> wrote:

> On Mon, 3 Aug 2026 16:39:55 +0100
> David Laight <david.laight.linux@gmail.com> wrote:
> 
> > On Mon, 3 Aug 2026 10:49:40 -0400 (EDT)
> > Nicolas Pitre <nico@fluxnic.net> wrote:
> >   
> > > On Mon, 3 Aug 2026, David Laight wrote:
> > >     
> > > > The x86 instruction set only supports 32bit signed immediate values
> > > > for add/sub.
> > > > Replace the "ir" constraint with "er" to avoid build errors.
> > > > 
> > > > Found by a patch that added used mul_u64_add_u64_div_u64() to
> > > > do a rounding divide by 2^32 (perhaps not the best way to do this).
> > > > 
> > > > A quick grep only found one other affected file.      
> > > 
> > > Would be a good idea adding those cases to the test module.    
> > 
> > They fail to compile so it isn't a big deal.
> >   
> David, thanks for sorting this (and all for reviewing)
> 
> Seems like everyone is happy.  What route is this taking upstream?
> 
> I held Rodrigo's driver to avoid the build breakage and would like to
> get it queued up early in next cycle.  So not that urgent but nice
> to be able to tick it off the list!
> 

Given I have a driver queued up behind this, shall I just take it through
the drivers/iio tree?

I can do an immutable branch just in case anyone else needs it this cycle.

Jonathan


> Thanks,
> 
> Jonathan
> 
> > 	David
> >   
> > > 
> > > 
> > > Nicolas    
> >   
>