symbol maintenance

symbol maintenance

[Fabian Cenedese]

Hello

After loading a file (without starting anything) I tried "maintenance check-symbols".
I got lots of messages like:

Global symbol `__7fixed32' only found in ..(path)..\Inos_typ.cpp psymtab
Global symbol `IntOf__7fixed64' only found in ..(path)..\Inos_typ.cpp psymtab
Global symbol `__7fixed64' only found in ..(path)..\Inos_typ.cpp psymtab
Global symbol `__ml__FG7fixed32T0' only found in ..(path)..\Inos_typ.cpp psymtab
Global symbol `__ml__FG7fixed64T0' only found in ..(path)..\Inos_typ.cpp psymtab

Is this something to worry about? Does this indicate wrong debug info or an
error in gdb? If it's nothing to worry about what's the use of these messages?
Only for gdb interna?

This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.

I:\cyghome\data\gdb-6.5\gdb>gdb --readnow
GNU gdb 6.5
..(GPL)...
This GDB was configured as "--host=i686-pc-cygwin --target=powerpc-eabi".
Setting up the environment for debugging gdb.
No symbol table is loaded.  Use the "file" command.
No symbol table is loaded.  Use the "file" command.
/data/gdb-6.5/gdb/.gdbinit:8: Error in sourced command file:
No breakpoint number 0.
(gdb) file gccext3.x
Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
panding to full symbols...unsupported const value attribute form: 'DW_FORM_strin
g'...const value length mismatch for 'ciOffline', got 8, expected 0...done.

Are these warnings something to worry about?

Thanks

bye   Fabi

Re: symbol maintenance

[Jim Blandy]

Fabian Cenedese <Cenedese@indel.ch> writes:
> After loading a file (without starting anything) I tried "maintenance check-symbols".
> I got lots of messages like:
>
> Global symbol `__7fixed32' only found in ..(path)..\Inos_typ.cpp psymtab
> Global symbol `IntOf__7fixed64' only found in ..(path)..\Inos_typ.cpp psymtab
> Global symbol `__7fixed64' only found in ..(path)..\Inos_typ.cpp psymtab
> Global symbol `__ml__FG7fixed32T0' only found in ..(path)..\Inos_typ.cpp psymtab
> Global symbol `__ml__FG7fixed64T0' only found in ..(path)..\Inos_typ.cpp psymtab
>
> Is this something to worry about? Does this indicate wrong debug info or an
> error in gdb? If it's nothing to worry about what's the use of these messages?
> Only for gdb interna?

I don't think those matter... I don't know for sure, but since those
are mangled C++ names, I'd expect that there's some kind of demangling
going on that's confusing the consistency checks.

> This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.
>
> I:\cyghome\data\gdb-6.5\gdb>gdb --readnow
> GNU gdb 6.5
> ..(GPL)...
> This GDB was configured as "--host=i686-pc-cygwin --target=powerpc-eabi".
> Setting up the environment for debugging gdb.
> No symbol table is loaded.  Use the "file" command.
> No symbol table is loaded.  Use the "file" command.
> /data/gdb-6.5/gdb/.gdbinit:8: Error in sourced command file:
> No breakpoint number 0.
> (gdb) file gccext3.x
> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
> panding to full symbols...unsupported const value attribute form: 'DW_FORM_strin
> g'...const value length mismatch for 'ciOffline', got 8, expected 0...done.

Those look more serious.  GDB is trying to read DWARF debugging
information, and it's malformed.  What compiler are you using?  What
does 'objdump -h gccext3.x' say?

Re: symbol maintenance

[Fabian Cenedese]

>> This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.
>>
>> (gdb) file gccext3.x
>> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
>> panding to full symbols...unsupported const value attribute form: 'DW_FORM_strin
>> g'...const value length mismatch for 'ciOffline', got 8, expected 0...done.
>
>Those look more serious.  GDB is trying to read DWARF debugging
>information, and it's malformed.  What compiler are you using?  What
>does 'objdump -h gccext3.x' say?

The used compiler is gcc 4.0.2, cross compiled for ppc.
The files for gccext3 were compiled with -gdwarf-2 (no +, no O).

Output of objdump -h gccext3.x:
(Sections 0, 15-18 are selfmade, necessary for the embedded target)

gccext3.x:     file format elf32-big

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .vtable       00001444  00000000  00000000  00010000  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  1 .text         00099ff0  00001444  00001444  00011444  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  2 .rodata       0000b720  0009b438  0009b438  000ab438  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  3 .eh_frame     00000970  000a6b58  000a6b58  000b6b58  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .ctors        000000d8  000a74c8  000a74c8  000b74c8  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  5 .dtors        00000018  000a75a0  000a75a0  000b75a0  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  6 .got2         000002b0  000a75b8  000a75b8  000b75b8  2**0
                  CONTENTS, ALLOC, LOAD, DATA
  7 .fixup        00000448  000a7868  000a7868  000b7868  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  8 .gcc_except_table 000000c8  000a7cb0  000a7cb0  000b7cb0  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  9 .comment      00000ccf  000a7d78  000a7d78  000cbae4  2**0
                  CONTENTS, READONLY
 10 .data         0000112c  000a8a48  000a8a48  000b8a48  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 11 .sdata        000000b0  000a9b74  000a9b74  000b9b74  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 12 .sbss         00000358  000a9c24  000a9c24  000b9c24  2**2
                  ALLOC
 13 .sdata2       00000000  000a9f7c  000a9f7c  000b9f7c  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 14 .bss          000028cc  000a9f80  000a9f80  000b9f7c  2**4
                  ALLOC
 15 .startup      0000f270  000ac84c  000ac84c  000bc84c  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 16 .struct_def   00000014  000bbabc  000bbabc  000cbabc  2**0
                  CONTENTS, ALLOC, LOAD, DATA
 17 .struct_nam   00000014  000bbad0  000bbad0  000cbad0  2**0
                  CONTENTS, ALLOC, LOAD, DATA
 18 .cache        00000000  000bc000  000bc000  000cc7b3  2**0
                  CONTENTS
 19 .debug_abbrev 0001748c  00000000  00000000  000cc7b3  2**0
                  CONTENTS, READONLY, DEBUGGING
 20 .debug_info   000d77c6  00000000  00000000  000e3c3f  2**0
                  CONTENTS, READONLY, DEBUGGING
 21 .debug_line   000189ba  00000000  00000000  001bb405  2**0
                  CONTENTS, READONLY, DEBUGGING
 22 .debug_frame  00014528  00000000  00000000  001d3dc0  2**2
                  CONTENTS, READONLY, DEBUGGING
 23 .debug_pubnames 00016f20  00000000  00000000  001e82e8  2**0
                  CONTENTS, READONLY, DEBUGGING
 24 .debug_aranges 000030d0  00000000  00000000  001ff208  2**0
                  CONTENTS, READONLY, DEBUGGING
 25 .debug_str    0000b420  00000000  00000000  002022d8  2**0
                  CONTENTS, READONLY, DEBUGGING
 26 .debug_loc    0001c2b9  00000000  00000000  0020d6f8  2**0
                  CONTENTS, READONLY, DEBUGGING
 27 .debug_ranges 00001890  00000000  00000000  002299b1  2**0
                  CONTENTS, READONLY, DEBUGGING
 28 .stab         00005004  00000000  00000000  0022b244  2**2
                  CONTENTS, READONLY, DEBUGGING
 29 .stabstr      00002466  00000000  00000000  00230248  2**0
                  CONTENTS, READONLY, DEBUGGING

Thanks

bye  Fabi

Re: symbol maintenance

[Jim Blandy]

Fabian Cenedese <Cenedese@indel.ch> writes:
>>> This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.
>>>
>>> (gdb) file gccext3.x
>>> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
>>> panding to full symbols...unsupported const value attribute form: 'DW_FORM_strin
>>> g'...const value length mismatch for 'ciOffline', got 8, expected 0...done.
>>
>>Those look more serious.  GDB is trying to read DWARF debugging
>>information, and it's malformed.  What compiler are you using?  What
>>does 'objdump -h gccext3.x' say?
>
> The used compiler is gcc 4.0.2, cross compiled for ppc.
> The files for gccext3 were compiled with -gdwarf-2 (no +, no O).

Oh, so you have an ELF file, not a PE file.  In that case, could you
run 'readelf -wi gccext3.x', and post the output?  If the DWARF in
that file is valid, and GDB's reading it properly, then the problem is
that GCC is producing information GDB can't use.

But even in that case, GDB should be able to properly skip data it
doesn't understand (DWARF is very good about that), so the answer to
your original question is, no, you don't need to worry about that
warning --- unless you're trying to use string constants and GDB
doesn't seem to know their values.

Re: symbol maintenance

[Fabian Cenedese]

>>>> (gdb) file gccext3.x
>>>> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
>>>> panding to full symbols...unsupported const value attribute form: 'DW_FORM_strin
>>>> g'...const value length mismatch for 'ciOffline', got 8, expected 0...done.
>>>
>>>Those look more serious.  GDB is trying to read DWARF debugging
>>>information, and it's malformed.  What compiler are you using?  What
>>>does 'objdump -h gccext3.x' say?
>>
>> The used compiler is gcc 4.0.2, cross compiled for ppc.
>> The files for gccext3 were compiled with -gdwarf-2 (no +, no O).
>
>Oh, so you have an ELF file, not a PE file.  In that case, could you
>run 'readelf -wi gccext3.x', and post the output?  If the DWARF in
>that file is valid, and GDB's reading it properly, then the problem is
>that GCC is producing information GDB can't use.
>
>But even in that case, GDB should be able to properly skip data it
>doesn't understand (DWARF is very good about that), so the answer to
>your original question is, no, you don't need to worry about that
>warning --- unless you're trying to use string constants and GDB
>doesn't seem to know their values.

I uploaded the output (11MB uncompressed, 1MB zipped) here:
http://www.speedyshare.com/512483789.html

I looked for the definition of this mismatch variable in the source. It's:

typedef signed char int8;
const int8 ciOffline = 254;

254 for a signed char is not really nice, but that alone shouldn't
confuse gdb or gcc, right?

 <2><6774b>: Abbrev Number: 92 (DW_TAG_variable)
     DW_AT_name        : ciOffline      
     DW_AT_decl_file   : 6      
     DW_AT_decl_line   : 142    
     DW_AT_type        : <685a0>        
     DW_AT_external    : 1      
     DW_AT_declaration : 1      
     DW_AT_const_value : 8 byte block: ff ff ff ff ff ff ff fe  

I don't know what variable or entry would cause the "unsupported const
value attribute form:'DW_FORM_string'", I can't find that string.

Thanks

bye  Fabi

Re: symbol maintenance

[Fabian Cenedese]

At 11:42 28.11.2006 -0800, Jim Blandy wrote:

>Fabian Cenedese <Cenedese@indel.ch> writes:
>>>> This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.
>>>>
>>>> (gdb) file gccext3.x
>>>> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
>>>> panding to full symbols...unsupported const value attribute form: 'DW_FORM_string'...

Got it, this warning comes from a variable defined as:

const char systemTable[] = "SYSTEM";

The warning is output in dwarf2_const_value where there really is no
case for DW_FORM_string.

bye  Fabi

Re: symbol maintenance

[Fabian Cenedese]

At 11:53 29.11.2006 +0100, you wrote:
>At 11:42 28.11.2006 -0800, Jim Blandy wrote:
>
>>Fabian Cenedese <Cenedese@indel.ch> writes:
>>>>> This is a gdb 6.5 cross-compiled with cygwin on WinXP for ppc.
>>>>>
>>>>> (gdb) file gccext3.x
>>>>> Reading symbols from /data/gdb-6.5/gdb/gccext3.x...unknown symbol type 0x1e...ex
>>>>> panding to full symbols...unsupported const value attribute form: 'DW_FORM_string'...
>
>Got it, this warning comes from a variable defined as:
>
>const char systemTable[] = "SYSTEM";
>
>The warning is output in dwarf2_const_value where there really is no
>case for DW_FORM_string.

Ack, actually that's wrong, this variable has type DW_FORM_strp.
The DW_FORM_string is produced by:

static char aStructNamebasetable[] = "Base";

bye  Fabi