[OE-core] [PATCH 0/4] base/bbclass: use target path to replace build ones in debugging info

[Hongxu Jia]

On 01/29/2016 01:04 AM, Richard Purdie wrote:
> On Thu, 2016-01-28 at 10:58 +0800, Hongxu Jia wrote:
>> On 01/28/2016 06:13 AM, Richard Purdie wrote:
>>> On Wed, 2016-01-27 at 14:34 -0500, Khem Raj wrote:
>>>>> On Jan 27, 2016, at 5:16 AM, Richard Purdie <
>>>>> richard.purdie at linuxfoundation.org> wrote:
>>>>>
>>>>> I like the idea of this a lot, I think it makes sense however
>>>>> why
>>>>> not
>> My original trying was just added them here, but the variable parsing
>> at here is too early, the ${BPN}, ${B} and {S} was assigned with
>> 'defaultpkgname' at this time. Which we have:
>> ...
>>> -fdebug-prefix-map=/buildarea/raid0/hjia/build-20160127-yocto
>>> -buildpath-2/
>> tmp/work/core2-64-poky-linux/defaultpkgname/1.0-r0/defaultpkgname
>> -1.0=
>> /usr/src/defaultpkgname
>
> I think this is just from your debugging technique. By the time these
> are used in recipes, they will have the correct value for these
> variables. Expansion happens late, not when the line is parsed.

For var DEBUG_FLAGS, it indeed has correct value at last, but the CFLAGS
and TARGET_CFLAGS was expanded when DEBUG_FLAGS has 'defaultpkgname'

The CFLAGS and TARGET_CFLAGS is shell variables (export CFLAGS=), it
seems shell variable is expanded only once.

>
> Can you be more specific about how you tested this and the problem you
> saw?

1. Modify bitbake.conf
diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index e80ee18..3ddb9e8 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -546,7 +546,14 @@ EXTRA_OEMAKE_prepend_task-install = 
"${PARALLEL_MAKEINST} "
  ##################################################################
  # Optimization flags.
  ##################################################################
-DEBUG_FLAGS ?= "-g -feliminate-unused-debug-types"
+DEBUG_FLAGS ?= "-g \
+    -feliminate-unused-debug-types \
+    -fdebug-prefix-map=${B}=/usr/src/${BPN} \
+    -fdebug-prefix-map=${S}=/usr/src/${BPN} \
+    -gno-record-gcc-switches \
+    -fdebug-prefix-map=${STAGING_DIR_NATIVE}= \
+    -fdebug-prefix-map=${STAGING_DIR_HOST}= \
+"

2. Build lib32-glibc, there are still buildpath QA Warnings
...
$ bitbake lib32-glibc
ERROR: QA Issue: File 
work/core2-32-pokymllib32-linux/lib32-glibc/2.22-r0/packages-split/lib32-glibc-dev/usr/lib/crt1.o 
in package contained reference to tmpdir
...

3. vim temp/run.do_compile
...
export 
TARGET_CFLAGS="-I/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/lib32-qemux86-64/usr/include 
-O2 -pipe -g -feliminate-unused-debug-types 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/work/core2-64-poky-linux/defaultpkgname/1.0-r0/defaultpkgname-1.0=/usr/src/defaultpkgname 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/work/core2-64-poky-linux/defaultpkgname/1.0-r0/defaultpkgname-1.0=/usr/src/defaultpkgname 
-gno-record-gcc-switches 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/x86_64-linux= 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/qemux86-64= 
"

export 
CFLAGS="-I/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/lib32-qemux86-64/usr/include 
-O2 -pipe -g -feliminate-unused-debug-types 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/work/core2-64-poky-linux/defaultpkgname/1.0-r0/defaultpkgname-1.0=/usr/src/defaultpkgname 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/work/core2-64-poky-linux/defaultpkgname/1.0-r0/defaultpkgname-1.0=/usr/src/defaultpkgname 
-gno-record-gcc-switches 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/x86_64-linux= 
-fdebug-prefix-map=/buildarea/raid0/hjia/build-20160128-yocto-buildpath2/tmp/sysroots/qemux86-64= 
"
...

>> With searching the manual, I could not find a gcc option to
>> do the path substitution on switches in debugging information.
>>
>> Maybe we could add a patch for gcc to do this. I could try in V2
>> if there is no side effect.
> I like that idea.

I have sent a simple modification on gcc in V2, it adds
a new option to not record  '-fdebug-prefix-map' to gcc
command line switches in debugging information.

//Hongxu

>> Compile with '-fdebug-prefix-map':
>> objdump -g packages-split/lib32-glibc-dev/usr/lib/gcrt1.o
>> ...
>>> <0><5e>: Abbrev Number: 1 (DW_TAG_compile_unit)
>>>     <5f>   DW_AT_producer    : (indirect string, offset: 0xbb): GNU
>>> C99 5.3.0 -m32
>> -march=core2 -mtune=core2 -msse3 -mfpmath=sse -mpreferred-stack
>> -boundary=4 -g -O2
>> -std=gnu99 -fgnu89-inline -fdebug-prefix
>> -map=/buildarea/raid0/hjia/build-20160119-
>> yocto-buildpath/tmp/work/core2-32-pokymllib32-linux/lib32-glibc/2.22
>> -r0/git=/usr/src/glibc
>> -feliminate-unused-debug-types -fmerge-all-constants -frounding-math
>> -ftls-model=initial-exec
>>
>> When we use '-fdebug-prefix-map', the TMPDIR was added to switches.
>> Although
>> remove the switches is to avoid buildpath QA check, the side effect
>> is
>> the other
>> part of compile options have also been removed.
>>
>> If we need to leave the switches in, I think we could tweak the
>> buildpath QA check,
>> which allows TMPDIR in '-fdebug-prefix-map=' without warning. I think
>> I
>> should
>> send a V2 to do this for discussion.
>>
>> Solution1: do some path substitutions on the switches
>> Solution2: tweak buildpath QA check to allow TMPDIR in '-fdebug
>> -prefix-map='
>>
>> I will try them in V2.
> Thanks, that part looks good to me.
>
> Cheers,
>
> Richard