Re: [PATCH v8 3/3] y2038: linux: Provide __clock_settime64 implementation

[Lukasz Majewski <lukma at denx dot de>]

Hi Joseph,

> Hi Joseph,
> 
> > On Wed, 18 Sep 2019, Lukasz Majewski wrote:
> >   
> > > Tests:
> > > - The code has been tested with x86_64/x86 (native compilation):
> > > make PARALLELMFLAGS="-j8" && make xcheck PARALLELMFLAGS="-j8"
> > > 
> > > - Run specific tests on ARM/x86 32bit systems (qemu):
> > > https://github.com/lmajewski/meta-y2038
> > > and run tests:
> > > https://github.com/lmajewski/y2038-tests/commits/master
> > > on kernels with and without 64 bit time support.    
> > 
> > Could you give more details of the configurations (including kernel 
> > headers version, --enable-kernel version, kernel version used at
> > runtime) for which you have built glibc and run the full glibc
> > testsuite?  I suspect this code is pretty close to being ready to go
> > in - but such patches have plenty of scope for mistakes (such as
> > were in earlier RV32 patch versions) such as typos, transposed
> > parameters, etc., that are hard for humans to spot reliably and
> > easy for compilers and testsuites to spot, so it's important to
> > know that sufficient automated tests have been run to catch any
> > such mistakes. 
> 
> So I tested this on ARM32 QEMU BSP build with meta-y2038 [1].
> 
> I. Build testing:
> - Machine's
> MACHINE=qemux86-64-x32
> MACHINE=qemux86-64
> MACHINE=qemux86
> MACHINE=qemuarm
> 
> - Using glib's
> test-wrapper='/opt/Y2038/glibc/src/scripts/cross-test-ssh.sh
> 
> for qemu ARM.
> 
> - ../src/scripts/build-many-glibcs.py
> 
> 
> II. Runtime testing - with BSP [1]:
> runqemu -d y2038arm nographic
> 
> - PREFERRED_VERSION_linux-y2038 = "5.1%" &&
>   Y2038_GLIBC_MIN_KERNEL_VERSION="5.1.0"
>   --enable-kernel=${Y2038_GLIBC_MIN_KERNEL_VERSION}
> 
>   Linux y2038arm 5.1.21-y2038-4a9b1eb8bc3ba4ad8b3b1aa3317cf8d4a3aaad83
> 
>   (Support __ASSUME_TIME64_SYSCALLS defined)
> 
> - Only PREFERRED_VERSION_linux-y2038 = "5.1%" - the minimal kernel
>   version is default one for current mainline glibc
> 
>   (The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports
>   __clock_settime64 syscalls).
> 
> - PREFERRED_VERSION_linux-lts = "4.19%"
>   with default minimal kernel version for contemporary glibc
>   (SHA1: 87accae3978c77c1a50d19ea8e3da3f0248d2612)
> 
>   This kernel doesn't support __clock_settime64 syscalls, so we
>   fallback to clock_settime.
> 
> Above tests are performed with Y2038 redirection applied [2] as well
> as without (so the __TIMESIZE != 64 execution path is checked as
> well).
> 
> III. Syscalls unit tests - test_y2038 program [3] installed on BSP.
> 
> IV. For x86_64 I do run the - as I can do it on my HOST PC
> 
> make PARALLELMFLAGS="-j8" && make xcheck PARALLELMFLAGS="-j8"
> 
> (before and after the patchset).
> 
> > I gave a list in 
> > <https://sourceware.org/ml/libc-alpha/2019-08/msg00234.html> of
> > five configurations I think are relevant to cover the different
> > cases in patches such as this ("new" = 5.1 or later; Florian's
> > changes to provide syscall tables in glibc would allow "#ifdef
> > __NR_clock_settime64" to be removed and eliminate case (b)):
> > 
> > (a) one that has always had 64-bit time, e.g. x86_64;
> >   
> 
> Point IV.

For this point I've only used make && make xcheck

> 
> > (b) one with 32-bit time and old kernel headers (any kernel version
> > at runtime);  
> 
> Point II.
> 
> > 
> > (c) one with 32-bit time and new kernel headers, old kernel at
> > runtime;
> > 
> > (d) one with 32-bit time and new kernel headers, new kernel at
> > runtime but no --enable-kernel;

Point c) and d) test scenario as described:

https://github.com/lmajewski/meta-y2038


> > 
> > (e) one with 32-bit time and new kernel at runtime and new 
> > --enable-kernel.  
> 
> Point II.
> 
> >   
> 
> I will double check if the above points are in sync with points a) to
> e).
> 
> > If some of these are problematic to test, you can ask for help
> > testing them.  For *this particular* patch you might not need to
> > test both (c) and (d), because they are identical as far as
> > compilation is concerned and the testsuite doesn't really cover
> > execution of clock_settime anyway.  But it's in the nature of the
> > Y2038 changes - involving lots of conditional code - that it's
> > necessary to test in several different configurations to cover the
> > conditionals adequately.  
> 
> QEMU (and OE/Yocto) helps here ...
> 
> > 
> > (For avoidance of doubt, it is *not* necessary to run
> > build-many-glibcs.py for this patch, and nor would running
> > build-many-glibcs.py be sufficient since it doesn't do execution
> > testing or cover the kernel headers version and --enable-kernel
> > variants.)
> >   
> 
> The build-many-glibcs helps with checking if there aren't some odd
> build breaks. It is one of many test approaches for testing the Y2038
> problem.
> 
> Note:
> 
> [1] - https://github.com/lmajewski/meta-y2038
> [2] -
> https://github.com/lmajewski/y2038_glibc/commit/1229b54508d0bb130a017a5b5591209167255665
> [3] - https://github.com/lmajewski/y2038-tests/commits/master
> 
> Best regards,
> 
> Lukasz Majewski
> 
> --
> 
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> lukma@denx.de




Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

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