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

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 1 Sep 2026 17:51:01 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> 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.
> 

I went ahead and picked these up on
https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git ib-iio-x86-asm-fix-7.3
and merged that into the main IIO branch. I want to give plenty of time in next
for the driver that was relying on them.

Currently this is all in my testing branch but I'll push that out as a non rebasing
(ideally) branch a bit later in the week.

Thanks

Jonathan

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