Re: [PATCH] usertools: rewrite pmdinfo

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, Sep 13, 2022 at 12:58:11PM +0200, Robin Jarry wrote:
> dpdk-pmdinfo.py does not produce any parseable output. The -r/--raw flag
> merely prints multiple independent JSON lines which cannot be fed
> directly to any JSON parser. Moreover, the script complexity is rather
> high for such a simple task: extracting PMD_INFO_STRING from .rodata ELF
> sections. Rewrite it so that it can produce valid JSON.
> 
> Remove the PCI database parsing for PCI-ID to Vendor-Device names
> conversion. This should be done by external scripts (if really needed).
> 

Thanks for the rework. Comment inline below.

/Bruce

<snip>

> +    :raises FileNotFoundError:
> +    """
> +    folders = []
> +    if "LD_LIBRARY_PATH" in os.environ:
> +        folders += os.environ["LD_LIBRARY_PATH"].split(":")
> +    folders += ["/usr/lib64", "/lib64", "/usr/lib", "/lib"]

This is a standard set of folders for Redhat and similar based
distributions, but not for Ubuntu and Debian ones - which use e.g.
"/lib/x86_64-linux-gnu". It's also missing path options from /usr/local,
which is a likely location for a compiled and installed DPDK.

Ideally, the script would parse the entries from /etc/ld.so.conf, or
/etc/ld.so.conf.d/* files to get a full list of directories to search on
the system. Frankly, though, that seems like too much work. :-) 
Two ideas I'd suggest, though both involve shelling out to other commands:

* Call "ldd" to get the paths to the relevant libraries for the current
  object, rather than parsing the DT_NEEDED entries from the elf file in
  the script
* Use "ldconfig -p" to get the list of libs and paths for the script and
  use that for matching the DT_NEEDED entries.