On 20/02/2022 21:11, Segher Boessenkool wrote:
On Sun, Feb 20, 2022 at 05:50:46PM +0000, Christophe Leroy wrote:
Le 20/02/2022 à 18:28, Mark Cave-Ayland a écrit :
On 19/02/2022 21:21, Segher Boessenkool wrote:
On Sat, Feb 19, 2022 at 12:06:50AM +0000, Mark Cave-Ayland wrote:
Thanks for the patch and the related links. From what I can see this looks correct and I see no issues debugging here, so I'll queue this for master pending any further comments (Segher?).
The patch is obviously correct.
But I have the same question I had with the simlar recent Linux patch: is it useful to have this debug info in Dwarf now, or is it not useful at all?
That is a good question. I'm assuming that since these symbols are still in upstream Linux then they have some utility? I don't think they would be useful on a day-to-day basis unless you were tracking down a compiler bug.
These symbols are going away in 5.18, see https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=...
There are no symbols going away. In fact, all debuggers may get enough information from the function symbols themselves, and the STABS info does not add anything. Oh wait, STABS info is encoded in artificial symbol table names, right.
The stuff removed from Linux is in the DSO; in OpenBIOS this is in its libgcc code. In GCC itself this code was removed in 2008, and it never has contained STABS info anyway. I have no idea what the OpenBIOS history here is, why the STABS was added in the first place.
As far as I can see in the OpenBIOS case the STABS info does not have any value-add. In the Linux case it is not so clear (there is more information encoded there, not just that some function name exists :-) )
So what's the history here? Was this code added to OpenBIOS from some other project?
My guess is that it was taken from historical gcc/Linux since that's where parts of the SPARC code come from. So given that Glenn's patch is echoing what's happening upstream, I'm inclined to take it as-is, and then a separate decision can be taken about the usefulness of the symbols later as they seem to cause no harm.
ATB,
Mark.