Bug 233616
| Summary: | gdb doesn't always display local variables in gcj-compiled applications | ||
|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Andrew Haley <aph> |
| Component: | gdb | Assignee: | Jan Kratochvil <jan.kratochvil> |
| Status: | CLOSED INSUFFICIENT_DATA | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | rawhide | CC: | cagney, jan.kratochvil, mjw, triage, tromey |
| Target Milestone: | --- | Keywords: | Reopened |
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Linux | ||
| Whiteboard: | bzcl34nup | ||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2008-05-07 01:19:35 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | |||
| Bug Blocks: | 233628 | ||
This works on i686:
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2bf70) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
(gdb) n
8 p.println("Arse");
(gdb) p p
$1 = java.io.PrintWriter@953c0
Could you please update the Fedora Core version?
"test2" was I believe for Fedora Core 1.
Not reproducible on RawHide.x86_64:
gdb-6.6-7.fc7.x86_64
gcc-java-4.1.2-5.x86_64
Not reproducible on FC6.x86_64:
gdb-6.5-15.fc6.x86_64
gcc-java-4.1.1-51.fc6.x86_64
Not reproducible on FC5.x86_64:
gdb-6.3.0.0-1.134.fc5.x86_64
gcc-java-4.1.1-1.fc5.x86_64
In all cases this script (for some versions two 'n's there or a different
function name syntax for FC5):
file ./a.out
b 'fh.main(java.lang.String[])void'
r
n
p p
set lang c++
p p
quit
prints:
Current language: auto; currently java
8 p.println("Arse");
$1 = java.io.PrintWriter@2aaaaea0f3e0
Warning: the current language does not match this frame.
$2 = (struct java.io.PrintWriter *) 0x2aaaaea0f3e0
I am using F7 Test 2.
If there were an "F7 Test 2" on the drop-down list I'd pick that. There isn't;
I don't know why.
My result with gdb 6.6-7.fc7rh gcc-java-4.1.2-5 and your script is:
Breakpoint 1 at 0x400c6b: file fh.java, line 7.
[Thread debugging using libthread_db enabled]
[New Thread 46912498391408 (LWP 19310)]
[New Thread 1084229952 (LWP 19325)]
[Switching to Thread 46912498391408 (LWP 19310)]
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaad08ee0) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
8 p.println("Arse");
$1 =
warning: RTTI symbol not found for class 'java::io::PrintWriter'
/home/aph/.gdbinit:5: Error in sourced command file:
Cannot access memory at address 0x0
It should be "devel" according to https://www.redhat.com/archives/fedora-devel-list/2007-March/msg00095.html It is still not reproducible for me, though, there may be other package dependencies. Please reproduce it on RH accessible RawHide.x86_64 machine. Going to check more later. This looks like a gdb regression between gdb 6.6-3 and 6.6-7.
Running on the same binary:
GNU gdb Red Hat Linux (6.6-3.fc7rh)
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaaaf8ee0) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
8 p.println("Arse");
$1 = java.io.PrintWriter@2aaaae2d6800
Warning: the current language does not match this frame.
$2 = (struct java.io.PrintWriter *) 0x2aaaae2d6800
GNU gdb Red Hat Linux (6.6-7.fc7rh)
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaaafaee0) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
8 p.println("Arse");
$1 =
warning: RTTI symbol not found for class 'java::io::PrintWriter'
/home/aph/.gdbinit:5: Error in sourced command file:
Cannot access memory at address 0x0
I've downgraded the box on which this fails to 6.6-3.fc7rh, and it still fails. So, this doesn't seem to vary with the version of gdb. On one machine with gdb version 6.6-3.fc7rh I get correct results, and on another machine with the exact same version of gdb I get incorrect results. This is when debugging the same binary. What else is there? Kernel changes, perhaps? These were the packages with files accessed during the gcj+gdb run: binutils-2.17.50.0.9-1.x86_64 gcc-4.1.2-1.x86_64 gcc-java-4.1.2-1.x86_64 glibc-2.5.90-17.x86_64 glibc-common-2.5.90-17.x86_64 glibc-devel-2.5.90-17.x86_64 libgcc-4.1.2-1.x86_64 libgcj-4.1.2-1.i386 libgcj-4.1.2-1.x86_64 libgcj-devel-4.1.2-1.x86_64 ncurses-5.6-5.20070217.fc7.i386 ncurses-5.6-5.20070217.fc7.x86_64 zlib-1.2.3-8.fc7.x86_64 zlib-devel-1.2.3-8.fc7.x86_64 Please also check there ARE / ARE NOT installed the -debuginfo packages the same way for the reproducibility. In my nonreproducible testcases there were NO -debuginfo packages installed. It would be also useful to attach here at least the resuling `a.out' file if it is reproducible with it. Yes, it's the debuginfo:
gdb ./a.out
GNU gdb Red Hat Linux (6.6-3.fc7rh)
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu"...
Using host libthread_db library "/lib64/libthread_db.so.1".
Breakpoint 1 at 0x400c6b: file fh.java, line 7.
[Thread debugging using libthread_db enabled]
[New Thread 46912496237696 (LWP 2977)]
[New Thread 1084229952 (LWP 3080)]
[Switching to Thread 46912496237696 (LWP 2977)]
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaaafaee0) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
8 p.println("Arse");
$1 =
warning: RTTI symbol not found for class 'java::io::PrintWriter'
/home/aph/.gdbinit:5: Error in sourced command file:
Cannot access memory at address 0x0
(gdb) quit
The program is running. Exit anyway? (y or n) y
zorro:~ $ sudo rpm -e gcc-debuginfo
zorro:~ $ /usr/bin/gdb ./a.out
GNU gdb Red Hat Linux (6.6-3.fc7rh)
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu"...
Using host libthread_db library "/lib64/libthread_db.so.1".
Breakpoint 1 at 0x400c6b: file fh.java, line 7.
[Thread debugging using libthread_db enabled]
[New Thread 46912496237696 (LWP 3144)]
[New Thread 1084229952 (LWP 3147)]
[Switching to Thread 46912496237696 (LWP 3144)]
Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaaafaee0) at fh.java:7
7 PrintWriter p = new PrintWriter("foobar");
Current language: auto; currently java
8 p.println("Arse");
$1 = java.io.PrintWriter@2aaaae33d160
Warning: the current language does not match this frame.
$2 = (struct java.io.PrintWriter *) 0x2aaaae33d160
The program is running. Exit anyway? (y or n) [answered Y; input not from terminal]
libjava part of gcc is now being compiled with -fno-rtti. Enabling it fails the libjava compilation. I believe it is a bug in GDB it should not require existing RTTI for C++/Java data and use just the static DWARF info instead. I was told I should reassign it to GCC and thus doing so. I expect the right way would be to fix GDB instead so please feel free to reassign it back. Sorry, Chris Feist, it was a typo. libgcj is built with -fno-rtti on purpose; gcj does not generate C++ RTTI, nor will it. gdb could also use the libgcj reflection info to print things. I have no idea how hard this is though. (In reply to comment #19) > libgcj is built with -fno-rtti on purpose; gcj does not generate C++ RTTI, > nor will it. Thanks, nice to know it really should not be needed for libjava and static DWARF is enough. > gdb could also use the libgcj reflection info to print things. > I have no idea how hard this is though. That would be a second step - FEAT, though. Based on the date this bug was created, it appears to have been reported against rawhide during the development of a Fedora release that is no longer maintained. In order to refocus our efforts as a project we are flagging all of the open bugs for releases which are no longer maintained. If this bug remains in NEEDINFO thirty (30) days from now, we will automatically close it. If you can reproduce this bug in a maintained Fedora version (7, 8, or rawhide), please change this bug to the respective version and change the status to ASSIGNED. (If you're unable to change the bug's version or status, add a comment to the bug and someone will change it for you.) Thanks for your help, and we apologize again that we haven't handled these issues to this point. The process we're following is outlined here: http://fedoraproject.org/wiki/BugZappers/F9CleanUp We will be following the process here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this doesn't happen again. This bug has been in NEEDINFO for more than 30 days since feedback was first requested. As a result we are closing it. If you can reproduce this bug in the future against a maintained Fedora version please feel free to reopen it against that version. The process we're following is outlined here: http://fedoraproject.org/wiki/BugZappers/F9CleanUp |
The problem is that gdb can't display local variables in Java mode, but it can display them in C++ mode. Here's a simple Java program: import java.io.*; public class fh { public static void main(String[] argv) throws Exception { PrintWriter p = new PrintWriter("foobar"); p.println("Arse"); p.close(); } } Compile it like this: /usr/bin/gcj fh.java --main=fh -g The debug it like this: $ gdb ./a.out (gdb) b 'fh.main(java.lang.String[])void' Breakpoint 1 at 0x400c6b: file fh.java, line 7. (gdb) r Starting program: /home/aph/a.out Breakpoint 1, fh.main(java.lang.String[])void (argv=@2aaaaad08ee0) at fh.java:7 7 PrintWriter p = new PrintWriter("foobar"); Current language: auto; currently java (gdb) n 8 p.println("Arse"); (gdb) p p $1 = warning: RTTI symbol not found for class 'java::io::PrintWriter' Cannot access memory at address 0x0 (gdb) set lang c++ Warning: the current language does not match this frame. (gdb) p p $2 = (class java.io.PrintWriter *) 0x2aaaae549160 Note that gdb returns a spurious "RTTI symbol not found" message and it fails to display the symbol's value.