XSB 2.0 beta 4 – Known Issue: Crash on some macOS systems due to AVX optimisations

Update: The hotfix is now available for download.

I’ve just tracked down the cause for a crash on some macOS systems which is related to the opus audio codec.

This bug affects all macOS systems that use CPUs that do not support AVX. AVX was introduced in 2011, so all mac systems from before 2011 will not currently work because of this issue. Mac systems from after 2011 that use an older CPU (such as the 2012 MacPro hex-core) also will not work.

The crash will be characterised by X-Plane crashing when a connection is made, or the audio setup dialogue being displayed. The macOS crashlog will indicate “Exception Type:        EXC_BAD_INSTRUCTION (SIGILL)” with the crashed thread crashing in mac.xpl at silk_VAD_Init + 4

Unfortunately, the opus team accidentally force-enabled AVX optimisations in their build tooling for opus, and so if the library is built on any AVX-capable mac, the result uses AVX, irrespective as to any options we set to inhibit that support.

I’ve patched the XSquawkBox libopus to disable this and as long as this doesn’t break the Linux build (the same options get used there), this update will be published as hotfix 2.

If you are using an old Mac – please hold off further bug reports until beta 4 hotfix 2 is published.

3 Replies to “XSB 2.0 beta 4 – Known Issue: Crash on some macOS systems due to AVX optimisations”

  1. I am not sure if my processor is outdated for AVX. I use a late 2013 iMac with 3,5 GHz Quad-Core Intel Core i7 (Turbo Boost up to 3,9 GHz), described by Apple. I think it should deal with AVX, but I am not sure.

    Unfortunately XP is crashing on startup with XSquawkbox b4 hotfix-2. The mac crashlog says EXC_BAD_ACCESS (SIGSEGV) as reason.

    XP log says:
    Attempting to start XSquawBox Plugin, version XSquawkBox VATSIM 2.0beta4.
    XSB: Couldn’t find dataref: sim/time/is_in_replay
    XSB: VATSIM Global Status found at “http://us.data.vatsim.net/vatsim-servers.txt”
    XSB: VATSIM Global Status found at “http://eu.data.vatsim.net/vatsim-servers.txt”
    XSB: VATSIM Global Status found at “http://apac.data.vatsim.net/vatsim-servers.txt”
    XSB: Got Server Details for “AFVDATA”
    XSB: Got Server Details for “CANADA”
    XSB: Got Server Details for “GERMANY-1”
    XSB: Got Server Details for “SINGAPORE”
    XSB: Got Server Details for “SYD-1”
    XSB: Got Server Details for “UK-1”
    XSB: Got Server Details for “USA-EAST”
    XSB: Got Server Details for “USA-WEST”
    XSB:AL: Created Source
    –=={This application has crashed because of the plugin: XSquawkBox/64/mac.xpl}==–

    1. This information isn’t useful in this form. Please fill out the bug report form – the form must have a complete, unedited, log.txt including the crash. If you know how to find the macos crashreport, please include that in your report.

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