Re: bug#48941: [powerpc64le-linux] libfaketime CLOCK_MONOTONIC test hangs

[Kaelyn <kaelyn.alexi@protonmail.com>]

Hi,

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Wednesday, July 21st, 2021 at 1:08 AM, Chris Marusich <cmmarusich@gmail.com> wrote:

> Hi,
>
> I need a little help figuring out how to use gdb in Guix for bug 48941:
>
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48941
>
> Here's the situation. A libfaketime test hangs forever. Upstream
>
> suggested I debug it. I'm trying to, but gdb errors out. What am I
>
> doing wrong? It's probably something simple, but I can't see what.
>
> I'll describe what I've done. First, I started a build like so:
>
> ./pre-inst-env guix build --keep-failed libfaketime
>
> While the problematic test hung, I found the PID of the test and killed
>
> it. This caused the build to fail, leaving the build environment for me
>
> to play around in.
>
> I entered a pure environment that contains all the things I need to
>
> debug the test (gcc 10.3.0 is currently the default gcc on
>
> core-updates):
>
> ./pre-inst-env guix environment --pure libfaketime --ad-hoc gcc-toolchain@10.3.0 gcc-toolchain@10.3.0:debug gdb
>
> In the pure environment, I confirmed I can build and run the hanging
>
> test via the following commands (I added -g in order to get debug
>
> symbols):
>
> make FAKETIME_COMPILE_CFLAGS='-DFORCE_MONOTONIC_FIX -g' CC=gcc PREFIX=/tmp/guix-build-libfaketime-0.9.9.drv-0/myprefix
>
> make FAKETIME_COMPILE_CFLAGS='-DFORCE_MONOTONIC_FIX -g' CC=gcc PREFIX=/tmp/guix-build-libfaketime-0.9.9.drv-0/myprefix test
>
> OK, so I can trigger the hang. Great! Next step, fire up GDB:
>
> --8<---------------cut here---------------start------------->8---
>
> [0] [env] marusich@suzaku:/tmp/guix-build-libfaketime-0.9.9.drv-0/source/test
>
> $ gdb ./timetest
>
> GNU gdb (GDB) 10.2
>
> Copyright (C) 2021 Free Software Foundation, Inc.
>
> License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
>
> This is free software: you are free to change and redistribute it.
>
> There is NO WARRANTY, to the extent permitted by law.
>
> Type "show copying" and "show warranty" for details.
>
> This GDB was configured as "powerpc64le-unknown-linux-gnu".
>
> Type "show configuration" for configuration details.
>
> For bug reporting instructions, please see:
>
> https://www.gnu.org/software/gdb/bugs/.
>
> Find the GDB manual and other documentation resources online at:
>
> http://www.gnu.org/software/gdb/documentation/.
>
> For help, type "help".
>
> Type "apropos word" to search for commands related to "word"...
>
> Reading symbols from ./timetest...
>
> (gdb)
>
> --8<---------------cut here---------------end--------------->8---
>
> The debug symbols provided by gcc-toolchain@10.3.0:debug are under
>
> $GUIX_ENVIRONMENT/lib/debug. This is the value of GUIX_ENVIRONMENT:
>
> --8<---------------cut here---------------start------------->8---
>
> $ echo $GUIX_ENVIRONMENT
>
> /gnu/store/32fjhp30k34fh0g9f1gmgcj8pc5wldq6-profile
>
> --8<---------------cut here---------------end--------------->8---
>
> By the way, this directory corresponds to glibc 2.33:
>
> --8<---------------cut here---------------start------------->8---
>
> $ realpath /gnu/store/32fjhp30k34fh0g9f1gmgcj8pc5wldq6-profile/lib/debug
>
> /gnu/store/8akrlhc25d7xvi85gzvginw0vdi4zyg4-glibc-2.33-debug/lib/debug
>
> --8<---------------cut here---------------end--------------->8---
>
> Let's tell GDB where to find those debug symbols:
>
> (gdb) set debug-file-directory /gnu/store/32fjhp30k34fh0g9f1gmgcj8pc5wldq6-profile/lib/debug
>
> Let's also tell GDB to set the environment variables that upstream
>
> recommended when running the test program:
>
> --8<---------------cut here---------------start------------->8---
>
> (gdb) set environment LD_PRELOAD=../src/libfaketime.so.1
>
> (gdb) set environment FAKETIME=-10d
>
> (gdb) set environment NO_FAKE_STAT=1
>
> --8<---------------cut here---------------end--------------->8---
>
> Now run it:
>
> --8<---------------cut here---------------start------------->8---
>
> (gdb) run
>
> Starting program: /tmp/guix-build-libfaketime-0.9.9.drv-0/source/test/timetest
>
> /bin/sh: /lib/powerpc64le-linux-gnu/libc.so.6: version `GLIBC_2.33' not found (required by ../src/libfaketime.so.1) /bin/sh: /lib/powerpc64le-linux-gnu/libc.so.6: version` GLIBC_2.32' not found (required by /gnu/store/kmblbljiygayhlc5gb02an9imhy90ws9-glibc-2.33/lib/libpthread.so.0)

Are you using Guix on a foreign distro? This line looks like your distro's normal libc.so was being used and it was from glibc-2.31 or older. The x86-64 systems I have that run pure Guix don't have any /lib*/ directories. You might try running gdb with LD_LIBRARY_PATH=/gnu/store/kmblbljiygayhlc5gb02an9imhy90ws9-glibc-2.33/lib to have the Guix libc.so picked up before the other one. HTH

Cheers,
Kaelyn

>
> /bin/sh: /lib/powerpc64le-linux-gnu/libc.so.6: version `GLIBC_2.32' not found (required by /gnu/store/kmblbljiygayhlc5gb02an9imhy90ws9-glibc-2.33/lib/libdl.so.2) /bin/sh: /lib/powerpc64le-linux-gnu/libc.so.6: version` GLIBC_2.32' not found (required by /gnu/store/kmblbljiygayhlc5gb02an9imhy90ws9-glibc-2.33/lib/librt.so.1)
>
> During startup program exited with code 1.
>
> (gdb)
>
> --8<---------------cut here---------------end--------------->8---
>
> Huh? What happened? I've double checked that I'm using gdb provided by
>
> Guix:
>
> --8<---------------cut here---------------start------------->8---
>
> $ type -P gdb
>
> /gnu/store/32fjhp30k34fh0g9f1gmgcj8pc5wldq6-profile/bin/gdb
>
> --8<---------------cut here---------------end--------------->8---
>
> I also tried running gdb by invoking it via that absolute file name, and
>
> it still errored out in the same way.
>
> I'm operating in a --pure environment. All the tools are provided by
>
> Guix. I'm surprised that /bin/sh and /lib are even mentioned above.
>
> If anyone can provide any advice, I'd be very grateful. I'm not sure
>
> how to proceed.
>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Chris