linux-kernel - Re: [PATCH rdma] IB/mlx5: Fix linkage failure on 32-bit arches

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Date:   Sun, 16 Feb 2020 20:36:10 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Maxim Mikityanskiy <maximmi@...lanox.com>
Cc:     Alexander Lobakin <alobakin@...nk.ru>,
        Leon Romanovsky <leon@...nel.org>,
        Doug Ledford <dledford@...hat.com>,
        Yishai Hadas <yishaih@...lanox.com>,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH rdma] IB/mlx5: Fix linkage failure on 32-bit arches

On Sun, Feb 16, 2020 at 01:53:50PM +0200, Maxim Mikityanskiy wrote:
> On 2020-02-14 21:44, Alexander Lobakin wrote:
> > Jason Gunthorpe wrote 14.02.2020 22:24:
> > > On Fri, Feb 14, 2020 at 10:13:09PM +0300, Alexander Lobakin wrote:
> > > > Commit f164be8c0366 ("IB/mlx5: Extend caps stage to handle VAR
> > > > capabilities") introduced a straight "/" division of the u64
> > > > variable "bar_size", which emits an __udivdi3() libgcc call on
> > > > 32-bit arches and certain GCC versions:
> > > > 
> > > > error: "__udivdi3" [drivers/infiniband/hw/mlx5/mlx5_ib.ko]
> > > > undefined! [1]
> > > > 
> > > > Replace it with the corresponding div_u64() call.
> > > > Compile-tested on ARCH=mips 32r2el_defconfig BOARDS=ocelot.
> > > > 
> > > > [1] https://lore.kernel.org/linux-mips/CAMuHMdXM9S1VkFMZ8eDAyZR6EE4WkJY215Lcn2qdOaPeadF+EQ@mail.gmail.com/
> > > > 
> > > > 
> > > > Fixes: f164be8c0366 ("IB/mlx5: Extend caps stage to handle VAR
> > > > capabilities")
> > > > Signed-off-by: Alexander Lobakin <alobakin@...nk.ru>
> > > >  drivers/infiniband/hw/mlx5/main.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > 
> > > Randy beat you too it..
> > > 
> > > https://lore.kernel.org/linux-rdma/20200206143201.GF25297@ziepe.ca/
> > 
> > Ah, OK. Sorry for missing this one. I didn't see any fix over
> > git.kernel.org and thought it doesn't exist yet.
> > 
> > > But it seems patchwork missed this somehow.
> > > 
> > > Applied now at least
> 
> Jason, I think Alexander's patch is more correct. It uses div_u64, while
> yours uses div64_u64. The divider is 32-bit, so div_u64 would be more
> optimized on most 32-bit architectures.

Seems so, but it is already done. You can send a followup to fix it

Jason