[PATCH v5 4/4] printk: use the lockless ringbuffer

[Nick Desaulniers]

>From what I can tell, I think this patch ("printk: use the lockless
ringbuffer") breaks lx-dmesg in CONFIG_GDB_SCRIPTS.

(gdb) lx-dmesg
Python Exception <class 'gdb.error'> No symbol "log_first_idx" in specified context.: 
Error occurred in Python: No symbol "log_first_idx" in specified context.

This command is used to dump the printk log buffer.

It looks like the only places left in the kernel that reference are:

- Documentation/admin-guide/kdump/gdbmacros.txt
- Documentation/admin-guide/kdump/vmcoreinfo.rst
- scripts/gdb/linux/dmesg.py

I believe this commit removed log_first_idx, so all of the above probably need
to be fixed up, too.

~ Nick