This is on Fedora 34 with elfutils-debuginfod-client-0.183-1.fc34.x86_64
In light of the bug #1970312 I wanted to be proactive and updated my .bashrc with:
export DEBUGINFOD_URLS=
(it's an empty string), as indicated at [1]. Now, when I run gdb with some project, it claims:
Download failed: Function not implemented. Continuing without debug info for /lib64/ld-linux-x86-64.so.2.
Download failed: Function not implemented. Continuing without debug info for /data/develop/local/evolution-data-server/system-supplied DSO at 0x7ffff7fc9000.
Download failed: Function not implemented. Continuing without debug info for /lib64/libc.so.6.
Download failed: Function not implemented. Continuing without debug info for /lib64/libpthread.so.0.
.....
there are like 50+ lines with various libraries listed.
I thought, when I set the URLS to an empty value, it'll be the same as when it's not set. When I `unset DEBUGINFOD_URLS`, then the messages from gdb are gone.
The [1] is not clear how to opt out, it should ideally provide a command, rather than vague description. I also believe the debuginfod should distinguish between existing & filled and existing & empty environment variable.
[1] https://fedoraproject.org/wiki/Changes/DebuginfodByDefault
I think this is a GDB bug. GDB is trying to be helpful by reporting the ENOSYS from debuginfod_find_debuginfo. But that simply means DEBUGINFOD_URLS isn't set (or empty) as stated in debuginfod_find_debuginfo (3) under ERRORS
ENOSYS $DEBUGINFOD_URLS is not defined.