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Re: Potential bug in openjdk-11 on mips64el



On 2/15/21 1:40 AM, Olek Wojnar wrote:
On Sat, Feb 13, 2021 at 2:21 PM <raphael.jolly@free.fr <mailto:raphael.jolly@free.fr>> wrote:
    It selects the "Zero" VM, which I assume is the one used on mips64el.
    https://openjdk.java.net/projects/zero/

Ah, thanks for the explanation! It helped me to appropriately adjust build-depends. Hmm, it looks like Zero is not supported on MIPS at the moment, but perhaps that site is just out-of-date?

There only Zero on mips64el for all current OpenJDKs. Zero for mips64el should be supported since JDK 10, see JDK-8186313: https://bugs.openjdk.java.net/browse/JDK-8186313

...so openjdk-11 is supposed to work.

On Sat, Feb 13, 2021 at 6:56 PM Tiago Daitx <tiago.daitx@canonical.com <mailto:tiago.daitx@canonical.com>> wrote:


    This seems to indicate that the isDirectory call [4] is getting wrong
    file attributes. Following the trail, those file attributes come from
    a fstatat call [5] which ultimately come from the native stack in
    UnixNativeDispatcher.c [6]. The actual way that fstatat is called
    depends on the build flags and defines from the arch, so somebody with
    better knowledge might want to take a look at UnixNativeDispatcher.c
    [6] and tell if OpenJDK is picking the right function to call for
    mips64el.


Thanks for the excellent analysis! So is this indeed a bug in OpenJDK on mips64el then? I'm happy to file the bug, referencing all of the information in this thread, if that's the probable culprit here.

Thing is, there is hardly anyone who supports mips64el in OpenJDK upstream. I think Debian folks are the most heavy users of it :) So, while you can submit a bug upstream, I don't think there is a high chance anyone picks it up. You can try to ask here:
  https://mail.openjdk.java.net/mailman/listinfo/mips-port

It looks to me that Zero mips64el is another instance of SecureDirectoryStream bug tail:
  https://bugs.openjdk.java.net/issues/?jql=text%20~%20%22SecureDirectoryStream%22

If there is the mips64el machine where this reproduces, the next step would be trying the mainline JDK NIO tests, something like:

 $ git clone https://github.com/openjdk/jdk
 $ cd jdk
 $ wget https://builds.shipilev.net/jtreg/jtreg.zip
 $ unzip jtreg.zip
 $ ./configure --with-debug-level=fastdebug --with-jtreg=./jtreg
 $ make run-test TEST=java/nio

...and if that does not yield failures, then MCVE would be needed.

--
Thanks,
-Aleksey


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