After update to current (as of now linux 4.17.14, and I just tested with 4.17.13 and the error is there too), valgrind fails with an 'impossible' error: ===== error start $ valgrind ./bin/opendir_readdir_dyn_char_basic ==1196== Memcheck, a memory error detector ==1196== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al. ==1196== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info ==1196== Command: ./bin/opendir_readdir_dyn_char_basic ==1196== valgrind: the 'impossible' happened: Unsupported arch_prctl option host stacktrace: ==1196== at 0x580441BA: show_sched_status_wrk (m_libcassert.c:355) ==1196== by 0x580442D4: report_and_quit (m_libcassert.c:426) ==1196== by 0x58044517: panic (m_libcassert.c:502) ==1196== by 0x58044517: vgPlain_core_panic_at (m_libcassert.c:507) ==1196== by 0x5804454A: vgPlain_core_panic (m_libcassert.c:512) ==1196== by 0x580DAE22: vgSysWrap_amd64_linux_sys_arch_prctl_before (syswrap-amd64-linux.c:286) ==1196== by 0x580A0C23: vgPlain_client_syscall (syswrap-main.c:1857) ==1196== by 0x5809D48A: handle_syscall (scheduler.c:1126) ==1196== by 0x5809EBB6: vgPlain_scheduler (scheduler.c:1443) ==1196== by 0x580AED50: thread_wrapper (syswrap-linux.c:103) ==1196== by 0x580AED50: run_a_thread_NORETURN (syswrap-linux.c:156) sched status: running_tid=1 Thread 1: status = VgTs_Runnable (lwpid 1196) ==1196== at 0x401A1C5: ??? (in /usr/lib/ld-2.28.so) ==1196== by 0x178BFBFE: ??? Note: see also the FAQ in the source distribution. It contains workarounds to several common problems. In particular, if Valgrind aborted or crashed after identifying problems in your program, there's a good chance that fixing those problems will prevent Valgrind aborting or crashing, especially if it happened in m_mallocfree.c. If that doesn't help, please report this bug to: www.valgrind.org In the bug report, send all the above text, the valgrind version, and what OS and version you are using. Thanks. ===== error end My question is does this look like an arch issue or is it just a kde upstream issue? I was answering a question on SO with a simple opendir/readdir of names into a dynamically allocated pointer-to-pointer-to-char and was showing how to test with valgrind. To my surprise valgrind croaked on Arch, but ran fine on SuSE and an old Arch box, so there is something wrong in the current valgrind on Arch. test source file at https://stackoverflow.com/questions/51804567/c-writing-readdir-to-char-array... (it just reads the contents of the directory given as the first argument ('.' default) and qsorts and outputs the stored names before freeing the names and pointers. -- David C. Rankin, J.D.,P.E.