On 1/15/21 1:53 PM, Sedat Dilek wrote:
On Fri, Jan 15, 2021 at 10:06 PM Nick Desaulniers
<ndesaulniers@xxxxxxxxxx> wrote:
DWARF v5 is the latest standard of the DWARF debug info format.
DWARF5 wins significantly in terms of size when mixed with compression
(CONFIG_DEBUG_INFO_COMPRESSED).
Link: http://www.dwarfstd.org/doc/DWARF5.pdf
Patch 1 is a cleanup from Masahiro and isn't DWARF v5 specific.
Patch 2 is a cleanup that lays the ground work and isn't DWARF
v5 specific.
Patch 3 implements Kconfig and Kbuild support for DWARFv5.
Changes from v4:
* drop set -e from script as per Nathan.
* add dependency on !CONFIG_DEBUG_INFO_BTF for DWARF v5 as per Sedat.
* Move LLVM_IAS=1 complexity from patch 2 to patch 3 as per Arvind and
Masahiro. Sorry it took me a few tries to understand the point (I
might still not), but it looks much cleaner this way. Sorry Nathan, I
did not carry forward your previous reviews as a result, but I would
appreciate if you could look again.
* Add Nathan's reviewed by tag to patch 1.
* Reword commit message for patch 3 to mention LLVM_IAS=1 and -gdwarf-5
binutils addition later, and BTF issue.
* I still happen to see a pahole related error spew for the combination
of:
* LLVM=1
* LLVM_IAS=1
* CONFIG_DEBUG_INFO_DWARF4
* CONFIG_DEBUG_INFO_BTF
Though they're non-fatal to the build. I'm not sure yet why removing
any one of the above prevents the warning spew. Maybe we'll need a v6.
En plus, I encountered breakage with GCC v10.2.1 and LLVM=1 and
CONFIG_DEBUG_INFO_DWARF4.
So might be good to add a "depends on !DEBUG_INFO_BTF" in this combination.
I suggested not to add !DEBUG_INFO_BTF to CONFIG_DEBUG_INFO_DWARF4.
It is not there before and adding this may suddenly break some users.
If certain combination of gcc/llvm does not work for
CONFIG_DEBUG_INFO_DWARF4 with pahole, this is a bug bpf community
should fix.
I had some other small nits commented in the single patches.
As requested in your previous patch-series, feel free to add my:
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
- Sedat -
Changes from v3:
Changes as per Arvind:
* only add -Wa,-gdwarf-5 for (LLVM=1|CC=clang)+LLVM_IAS=0 builds.
* add -gdwarf-5 to Kconfig shell script.
* only run Kconfig shell script for Clang.
Apologies to Sedat and Nathan; I appreciate previous testing/review, but
I did no carry forward your Tested-by and Reviewed-by tags, as the
patches have changed too much IMO.
Changes from v2:
* Drop two of the earlier patches that have been accepted already.
* Add measurements with GCC 10.2 to commit message.
* Update help text as per Arvind with help from Caroline.
* Improve case/wording between DWARF Versions as per Masahiro.
Changes from the RFC:
* split patch in 3 patch series, include Fangrui's patch, too.
* prefer `DWARF vX` format, as per Fangrui.
* use spaces between assignment in Makefile as per Masahiro.
* simplify setting dwarf-version-y as per Masahiro.
* indent `prompt` in Kconfig change as per Masahiro.
* remove explicit default in Kconfig as per Masahiro.
* add comments to test_dwarf5_support.sh.
* change echo in test_dwarf5_support.sh as per Masahiro.
* remove -u from test_dwarf5_support.sh as per Masahiro.
* add a -gdwarf-5 cc-option check to Kconfig as per Jakub.
*** BLURB HERE ***
Masahiro Yamada (1):
Remove $(cc-option,-gdwarf-4) dependency from CONFIG_DEBUG_INFO_DWARF4
Nick Desaulniers (2):
Kbuild: make DWARF version a choice
Kbuild: implement support for DWARF v5
Makefile | 13 +++++++---
include/asm-generic/vmlinux.lds.h | 6 ++++-
lib/Kconfig.debug | 42 +++++++++++++++++++++++++------
scripts/test_dwarf5_support.sh | 8 ++++++
4 files changed, 57 insertions(+), 12 deletions(-)
create mode 100755 scripts/test_dwarf5_support.sh
--
2.30.0.284.gd98b1dd5eaa7-goog
