[Buildroot] [PATCH 1/1] package/capnproto: fix build on riscv32

[Fabrice Fontaine <fontaine.fabrice@gmail.com>]

Le ven. 28 mai 2021 ? 17:25, Arnout Vandecappelle <arnout@mind.be> a ?crit :
>
>
>
> On 28/05/2021 16:33, Fabrice Fontaine wrote:
> > Hi Arnout,
> >
> > Le ven. 28 mai 2021 ? 16:17, Arnout Vandecappelle <arnout@mind.be> a ?crit :
> >>
> >>
> >>
> >> On 28/05/2021 09:11, Fabrice Fontaine wrote:
> >>> Hi Koen,
> >>>
> >>> Le ven. 28 mai 2021 ? 09:00, Koen Martens <gmc@sonologic.nl> a ?crit :
> >>>>
> >>>> Hi,
> >>>>
> >>>> Thanks for diving into this. I've had emails about this for months, and briefly
> >>>> looked at it, but never found the time to properly figure it out.
> >>>>
> >>>> I see the patch below is also present upstream. Do you know whether this has
> >>>> already been released or when it will be?
> >>> I don't know when upstream will release a new version.
> >>> However, after digging through a lot of riscv32 build failures on
> >>> other packages, I'm not sure that this upstream patch is right
> >>> anymore.
> >>> Aliasing SYS_futex to SYS_futex_time64 has been rejected by vlc for example:
> >>> https://patches.videolan.org/patch/30581/
> >>
> >>  That patch looks OK to me:
> >>
> >> +/* 32bit architectures with 64bit time_t do not define __NR_futex syscall */
> >> +#if !defined(SYS_futex) && defined(SYS_futex_time64)
> >> +#define SYS_futex SYS_futex_time64
> >> +#endif
> >>
> >>  The comment was "this patch won't work if the userspace ABI uses the
> >> 64-bit time_t on a 32-bit ISA that did start with 32-bit time_t" - but that's
> >> not true. On a 32-bit ISA that did start with 32-bit time_t, SYS_futex will be
> >> defined (or SYS_foo is not properly exported by libc and then SYS_futex_time64
> >> isn't defined either).
> >>
> >>  To be really safe, you should maybe also check that __TIMESIZE == 64 [1] - but
> >> that may break on musl or uClibc.
> >>
> >>  Or even better of course would be to patch all code to use the __time64_t
> >> instead of time_t everywhere, independent of __TIMESIZE. But even then you'd
> >> need fallback to time_t for old libc/kernel.
> > Thanks for your feedback, I'll then send a v2 of my patch for vlc to
> > fix the build on riscv32 instead of disabling it.
>
>  Well, no, only if upstream vlc is going to accept that approach.
OK, then feel free to apply v1 ;-)
>
>  Regards,
>  Arnout
>
> >>
> >>
> >>  Regards,
> >>  Arnout
> >>
> >>
> >> [1]
> >> https://www.gnu.org/software/libc/manual/html_node/64_002dbit-time-symbol-handling.html
> >>
> >>
> >>
> >>
> >>
> >>> So another option would be to just disable capnproto on riscv32.
> >>>>
> >>>> Given that this exact patch is also applied upstream, your patch below seems fine
> >>>> to me.
> >>>>
> >>>> Cheers,
> >>>>
> >>>> Koen
> >>>>
> >>>> On Thu, May 27, 2021 at 11:04:02PM +0200, Fabrice Fontaine wrote:
> >>>>> Fixes:
> >>>>>  - http://autobuild.buildroot.org/results/1c1cd4775241ee57d878cad5c978413d4b4a8736
> >>>>>
> >>>>> Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> >>>>> ---
> >>>>>  ...it-architectures-using-64-bit-time_t.patch | 37 +++++++++++++++++++
> >>>>>  1 file changed, 37 insertions(+)
> >>>>>  create mode 100644 package/capnproto/0001-mutex-Fix-build-on-32-bit-architectures-using-64-bit-time_t.patch
> >>>>>
> >>>>> diff --git a/package/capnproto/0001-mutex-Fix-build-on-32-bit-architectures-using-64-bit-time_t.patch b/package/capnproto/0001-mutex-Fix-build-on-32-bit-architectures-using-64-bit-time_t.patch
> >>>>> new file mode 100644
> >>>>> index 0000000000..ce70ab8f29
> >>>>> --- /dev/null
> >>>>> +++ b/package/capnproto/0001-mutex-Fix-build-on-32-bit-architectures-using-64-bit-time_t.patch
> >>>>> @@ -0,0 +1,37 @@
> >>>>> +From e2a05a19e9dc51287e19cc9f11fd91449219e361 Mon Sep 17 00:00:00 2001
> >>>>> +From: Khem Raj <raj.khem@gmail.com>
> >>>>> +Date: Sun, 15 Nov 2020 12:10:28 -0800
> >>>>> +Subject: [PATCH] mutex: Fix build on 32-bit architectures using 64-bit time_t
> >>>>> +
> >>>>> +mutex code uses SYS_futex, which it expects from system C library.
> >>>>> +in glibc (/usr/include/bits/syscall.h defines it in terms of of NR_futex)
> >>>>> +rv32 is using 64bit time_t from get go unlike other 32bit architectures
> >>>>> +in glibc, therefore it wont have NR_futex defined but just NR_futex_time64
> >>>>> +this aliases it to NR_futex so that SYS_futex is then defined for rv32
> >>>>> +
> >>>>> +Signed-off-by: Khem Raj <raj.khem@gmail.com>
> >>>>> +[Retrieved from:
> >>>>> +https://github.com/capnproto/capnproto/commit/e2a05a19e9dc51287e19cc9f11fd91449219e361]
> >>>>> +Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
> >>>>> +---
> >>>>> + c++/src/kj/mutex.c++ | 6 ++++++
> >>>>> + 1 file changed, 6 insertions(+)
> >>>>> +
> >>>>> +diff --git a/c++/src/kj/mutex.c++ b/c++/src/kj/mutex.c++
> >>>>> +index c81cead7b..e1594b117 100644
> >>>>> +--- a/c++/src/kj/mutex.c++
> >>>>> ++++ b/c++/src/kj/mutex.c++
> >>>>> +@@ -39,7 +39,13 @@
> >>>>> +
> >>>>> + #ifndef SYS_futex
> >>>>> + // Missing on Android/Bionic.
> >>>>> ++#ifdef __NR_futex
> >>>>> + #define SYS_futex __NR_futex
> >>>>> ++#elif defined(SYS_futex_time64)
> >>>>> ++#define SYS_futex SYS_futex_time64
> >>>>> ++#else
> >>>>> ++#error "Need working SYS_futex"
> >>>>> ++#endif
> >>>>> + #endif
> >>>>> +
> >>>>> + #ifndef FUTEX_WAIT_PRIVATE
> >>>>> --
> >>>>> 2.30.2
> >>>>>
> >>> Best Regards,
> >>>
> >>> Fabrice
> >>> _______________________________________________
> >>> buildroot mailing list
> >>> buildroot at busybox.net
> >>> http://lists.busybox.net/mailman/listinfo/buildroot
> >>>
> > Best Regards,
> >
> > Fabrice
> >
Best Regards,

Fabrice