Re: [RFC PATCH 00/10] x86: undwarf unwinder

From: Ingo Molnar
Date: Thu Jun 01 2017 - 02:08:32 EST



* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:

> Here's the contents of the undwarf.txt file which explains the 'why' in
> more detail:

Ok, so the code quality looks pretty convincing to me - the new core 'undwarf'
unwinder code is a _lot_ more readable than any of the Dwarf based attempts
before.

That we control the debug info generation at build time is icing on the cake to
me.

One thing I'd like to see on the list of benefits side of the equation is a size
comparison of kernel .text, with frame pointers vs. undwarf, on 64-bit kernels.

Being able to generate more optimal code in the hottest code paths of the kernel
is the _real_, primary upstream kernel benefit of a different debuginfo method -
which has to be weighed against the pain of introducing a new unwinder. But this
submission does not talk about that aspect at all, which should be fixed I think.

Thanks,

Ingo