[w3m-dev-en 00286] gcc -O2 in Linux (summary so far)

From: Ambrose Li (acli@ada.dhs.org)
Date: Tue Nov 14 2000 - 13:29:26 CST

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    Hi,

    On Tue, Nov 14, 2000 at 07:48:23AM +0100, Moritz Barsnick wrote:
    >
    > Have you tried following those links "manually", i.e. looking at the
    > source, fething the respective pages with "wget" or the likes, and
    > trying to display these files with w3m? Perhaps you can then trace the
    > error. Or start w3m with "gdb" or "ddd".

    Yes. The results are very strange; perhaps we should put "Don't use -O2
    if you use Linux + gcc" in the README, just as Brandon D. Valentine
    <bandix@looksharp.net> pointed out.

    However, there might be a real bug in w3m triggered by gcc, instead of
    just a bug in gcc triggered by w3m. So perhaps---or perhaps not---some
    more investigation is still needed. I don't know what this bug is, if
    there really is a bug.

    Summary of results so far:

    - This seems to be Linux-specific; Solaris and BSDI are not affected
    - This does not seem to be x86-specific
    - This does not seem to be gcc-version-specific
    - This may be proxy-related: different sequences or events will affect
      whether a crash occurs or not if a proxy is used; if a proxy is not
      used a crash apparently will not occur
    - This problem cannot be debugged using gdb
    - This problem is intermittent (not reliably reproducible)

    Details of results so far:

    I only got 2 replies with test data so far, one from Sven Mascheck
    <mascheck@faw.uni-ulm.de>; the other from Eliphas Levy Theodoro
    <eliphas@conectiva.com.br>.

    This seems to be Linux-specific. Solaris/SunOS is not affected, it
    seems, nor is BSDI (x86) affected; both Sven Mascheck and I tested this
    on Solaris, with no crash. I tested under BSDI (BSD/OS 4.0; gcc 2.7.2.1),
    with no crash.

    This seems to affect various versions of w3m and gcc. Both Eliphas Levy
    Theodoro and I tested this on Linux. Both w3m 0.1.10 and 0.1.11-dev are
    affected. Both egcs-2.90.29, gcc-2.95.2 (x86) and gcc-2.8.1 (armv4l) are
    affected. This does not seem to be x86-specific under Linux. Tested
    kernel versions are 2.2.16, 2.2.17 (x86) and 2.0.35 (armv4l).

    (The armv4l results may not be very accurate because my armv4l system
    does not exactly "work"---it's more of a pre-mass-production prototype
    than a production-quality system.)

    If I follow the link manually there is no problem. But then the link
    won't open inside a particular frame. When w3m crashes it is somewhere
    during frame rendering.

    Eliphas Levy Theodoro <eliphas@conectiva.com.br> suggested that this
    may be proxy-related (both Eliphas and I use a proxy), after observing
    the following behaviour (which I can reproduce):

    - Go to www.bild.de -> News -> Der Augenzeuge => Crash
    - Go to www.bild.de -> News
    - Enter link manually => No crash
    - Without leaving w3m, www.bild.de -> News -> Der Augenzeuge => No crash
    - Even if we leave w3m and retry the sequence, we may or may not get a
      crash

    If I use -no-proxy, I get no crash; this seem to confirm Eliphas'
    suspicion that the problem is proxy-related.

    If I use gdb there is no problem. Not even if I run w3m stand-alone and
    then attach to it from another terminal. No gdb, crash; gdb, no crash
    (^^;)

    > Wondering, just as much as you are,
    > Moritz. :)

    -- 
    óÕ ¼ß±É  <acli@ada.dhs.org>  http://trends.ca/~acli/
         ALARMED? RAISE THE ALARM!  http://www.adbusters.org/contest/
                        "A good style should show no sign of effort;
    what is written should seem a happy accident." -- Somerset Maugham.
    



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