Re: [EXT] Re: Slow "symbol-file" when using GDB 12.1 on Windows hosts

[Luis Machado <luis.machado@arm.com>]

On 4/3/23 17:48, Adrian Oltean wrote:
>> -----Original Message-----
>> From: Luis Machado <luis.machado@arm.com>
>> Sent: Wednesday, March 22, 2023 4:31 PM
>> To: Eli Zaretskii <eliz@gnu.org>; Adrian Oltean <adrian.oltean@nxp.com>
>> Cc: gdb@sourceware.org
>> Subject: Re: [EXT] Re: Slow "symbol-file" when using GDB 12.1 on Windows
>> hosts
>>
>>
>> The logic to lookup debug info is OS-invariant I think, but gdb does have to
>> adjust to the Windows-style paths.
>>
>> With that said, most of the attempts gdb does at accessing directories is an
>> attempt to locate separate debug info files or simply to locate shared library
>> symbol files.
>>
>> Since there is quite a bit of variation in terms of where an OS puts those files,
>> gdb has to use heuristics to try to determine those directories, so it will try to
>> access gdb-generated paths sometimes.
>>
>> It shouldn't slow things down though, as it is mostly a file open/close request.
> 
> Hi guys,
> 
> I managed to identify what's causing the described behavior. The CSC  folder is actually
> accessed indirectly because of the fact that a network share is attempted to be
> accessed by GDB on Windows - see paths like " \\lib\debug" in my previous emails.
> 
> The fact that GDB is trying to access (most likely invalid in almost all setups) network
> shares like " \\lib\debug" on Windows hosts, I'm pretty sure the slowdown isn't
> happening only for me (actually, all PCs from our organization). Note that this path
> is the one specific to latest GDB 12 build delivered by ARM:
> (gdb) show debug-file-directory
> The directory where separate debug symbols are searched for is "\\lib\debug".
> 
> For GDB 10 I see:
> (gdb) show debug-file-directory
> The directory where separate debug symbols are searched for is "c:\mnt\workspace\workspace\gcc-10-pipeline\jenkins-gcc-10-pipeline-338_20211018_1634516203\install-mingw\lib\debug".
> 
> As far as I can tell, ARM changed something in their build environment causing this
> unwanted effect. With this findings, I decided to workaround the problem by
> setting debug-file-directory to an empty value once GDB starts-up.

The default debug-file-directory gets set during configure/build. I don't think the previous path is correct, as it is obviously a path internal to the build machine.

GDB has relocatable paths that it adjusts based on where GDB is running on the target system. Those settings will be shown by the command Pedro suggested.

For instance, one of the entries:

--with-separate-debug-dir=/usr/lib/debug (relocatable)

With that said, \\lib\debug seems a a bit odd, and there might be something off there unless your filesystem is NFS-mounted.

> 
> Thanks,
> Adrian
> 
> 
>