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From:   Zong Li <zongbox@gmail.com>
Date:   Sat, 29 Sep 2018 11:40:37 +0800
Message-ID: <CA+ZOyagkLaikQjcwJzFumOs=o2Bhu0nzRcdb3a8fW7nT-HfprQ@mail.gmail.com>
Subject: Re: [PATCH v2 0/5] Fix some bugs on RV32 build fail and issue
To:     Palmer Dabbelt <palmer@sifive.com>
Cc:     hch@infradead.org, aou@eecs.berkeley.edu,
        Zong Li <zong@andestech.com>,
        Vincent Chen <vincentc@andestech.com>,
        linux-riscv@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Palmer Dabbelt <palmer@sifive.com> =E6=96=BC 2018=E5=B9=B49=E6=9C=8829=E6=
=97=A5 =E9=80=B1=E5=85=AD =E4=B8=8A=E5=8D=887:52=E5=AF=AB=E9=81=93=EF=BC=9A
>
> On Wed, 26 Sep 2018 01:31:09 PDT (-0700), zongbox@gmail.com wrote:
> > This patches contain the modificaion as follows:
> > 1. Fix up the building fail on RV32.
> > 2. Add umoddi3 and udivmoddi4 functions for RV32.
> > 3. Fix ioremap problem on RV32.
> >
> > Changes in v2:
> >  - Retain the copyright notices from libgcc in umoddi3.c and udivmoddi4=
.c.
> >
> > Vincent Chen (1):
> >   RISC-V: Avoid corrupting the upper 32-bit of phys_addr_t in ioremap
> >
> > Zong Li (4):
> >   RISC-V: Build tishift only on 64-bit
> >   RISC-V: Use swiotlb on RV64 only
> >   lib: Add umoddi3 and udivmoddi4 of GCC library routines
> >   RISC-V: Select GENERIC_LIB_UMODDI3 on RV32
> >
> >  arch/riscv/Kconfig        |   1 +
> >  arch/riscv/kernel/setup.c |   3 +
> >  arch/riscv/lib/Makefile   |   3 +-
> >  arch/riscv/mm/ioremap.c   |   2 +-
> >  lib/Kconfig               |   3 +
> >  lib/Makefile              |   1 +
> >  lib/udivmoddi4.c          | 309 ++++++++++++++++++++++++++++++++++++++=
++++++++
> >  lib/umoddi3.c             |  34 +++++
> >  8 files changed, 354 insertions(+), 2 deletions(-)
> >  create mode 100644 lib/udivmoddi4.c
> >  create mode 100644 lib/umoddi3.c
>
> I like what this does, but there's a license issue here that Christoph po=
inted
> out.  It'd be great to have RV32I systems booting 4.19, do you think ther=
e's a
> chance you can sort this out next week so we can get it into the last RC?=
  That
> would help with the rv32i glibc process, as we'll actually be able to boo=
t an
> upstream kernel.
>
> It looks like the functions we have an issue with come from libgcc2.c, wh=
ich
> doesn't change very much.  As far as I can tell we might be able to get a=
way
> with these functions from 4.2.1, which was licensed under the GPLv2.  Her=
e's
> the relevant functions on GCC's github mirror
>
>     https://github.com/gcc-mirror/gcc/blob/gcc-4_2_1-release/gcc/libgcc2.=
c#L559
>     https://github.com/gcc-mirror/gcc/blob/gcc-4_2_1-release/gcc/libgcc2.=
c#L844
>
> These look very similar to what you send out.  As far as I can tell, if y=
ou
> base your code on the GPLv2 version then this should be fine to include.
>
> Thanks!

Thanks for the help and useful information. I will modify the
implementation and submit the next version.