Re: undefined reference to `__aeabi_uldivmod' after 25c13324d03d ("IB/mlx5: Add steering SW ICM device memory type")

[Chen, Rong A]

Hi,

On 5/16/2019 10:21 AM, Fengguang Wu wrote:
> CC current 0day kbuild test maintainers Philip and Rong. -fengguang
>
> On Tue, May 14, 2019 at 11:49:18PM -0700, Nathan Chancellor wrote:
> > On Wed, May 15, 2019 at 08:42:13AM +0200, Arnd Bergmann wrote:
> > > On Wed, May 15, 2019 at 8:40 AM Nathan Chancellor
> > > <natechancellor@xxxxxxxxx> wrote:
> > > > On Wed, May 15, 2019 at 08:31:49AM +0200, Arnd Bergmann wrote:
> > > > > On Wed, May 15, 2019 at 7:04 AM Leon Romanovsky 
> > > <leonro@xxxxxxxxxxxx> wrote:
> > > > > > On Tue, May 14, 2019 at 09:32:02PM -0300, Jason Gunthorpe wrote:
> > > > > > > On Tue, May 14, 2019 at 12:45:10PM -0700, Nathan Chancellor 
> > > wrote:
> > > > > > > > Hi all,
> > > > > > > >
> > > > > > > > I checked the RDMA mailing list and trees and I haven't 
> > > seen this
> > > > > > > > reported/fixed yet (forgive me if it has) but when 
> > > building for arm32
> > > > > > > > with multi_v7_defconfig and the following configs 
> > > (distilled from
> > > > > > > > allyesconfig):
> > > > > > > >
> > > > > > > > CONFIG_INFINIBAND=y
> > > > > > > > CONFIG_INFINIBAND_ON_DEMAND_PAGING=y
> > > > > > > > CONFIG_INFINIBAND_USER_ACCESS=y
> > > > > > > > CONFIG_MLX5_CORE=y
> > > > > > > > CONFIG_MLX5_INFINIBAND=y
> > > > > > > >
> > > > > > > > The following link time errors occur:
> > > > > > > >
> > > > > > > > arm-linux-gnueabi-ld: drivers/infiniband/hw/mlx5/main.o: 
> > > in function `mlx5_ib_alloc_dm':
> > > > > > > > main.c:(.text+0x60c): undefined reference to 
> > > `__aeabi_uldivmod'
> > > > > > > > arm-linux-gnueabi-ld: drivers/infiniband/hw/mlx5/cmd.o: in 
> > > function `mlx5_cmd_alloc_sw_icm':
> > > > > > > > cmd.c:(.text+0x6d4): undefined reference to 
> > > `__aeabi_uldivmod'
> > > > > > > > arm-linux-gnueabi-ld: drivers/infiniband/hw/mlx5/cmd.o: in 
> > > function `mlx5_cmd_dealloc_sw_icm':
> > > > > > > > cmd.c:(.text+0x9ec): undefined reference to 
> > > `__aeabi_uldivmod'
> > > > > > >
> > > > > > > Fengguang, I'm surprised that 0-day didn't report this 
> > > earlier..
> > > > > >
> > > > > > I got many successful emails after I pushed this patch to 
> > > 0-day testing.
> > > > >
> > > > > The long division warnings can compiler specific, and depend on 
> > > certain
> > > > > optimization options, as compilers can optimize out certain 
> > > divisions and
> > > > > replace them with multiplications and/or shifts, or prove that 
> > > they can be
> > > > > replaced with a 32-bit division. If this is a case that gcc 
> > > manages to
> > > > > optimize but clang does not, it might be worth looking into 
> > > whether an
> > > > > optimization can be added to clang, in addition to improving the 
> > > source.
> > > >
> > > > While I did run initially run into this with clang, the errors 
> > > above are
> > > > with gcc (mainly to show this was going to be a universal problem and
> > > > not just something with clang).
> > >
> > > Which gcc version did you use here? Anything particularly old or 
> > > particularly
> > > new? I think 0-day is on a fairly recent gcc-8, but not the latest 
> > > gcc-9
> > > release.
> >
> > 8.2.0 it seems (I've been meaning to build from the 9.x branch though
> > since it appears that Arch's arm-linux-gnueabi-gcc isn't going to get
> > updated since it's in the AUR).
Thanks for the reminding, we met some problems with gcc 8.1.0 once,

then we uses "arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0" as the 
default gcc for arm,

It seems we have missed some build issues detected by new gcc. we're 
going to upgrade gcc ASAP.

Best Regards,
Rong Chen