[dpdk-dev] mk: add support for gdb debug info generation

  From: Cyril Chemparathy <cchemparathy@tilera.com>

It is often useful to build with debug enabled, we add a config
(CONFIG_RTE_TOOLCHAIN_DEBUG) to do so.

Note: This patch does not include corresponding changes for ICC.  The
author pleads abject ignorance in this regard, and welcomes
recommendations. :-)

Change-Id: I499e591e1b7d71df751fd40d1fdcbe6975eeeb27
Signed-off-by: Cyril Chemparathy <cchemparathy@ezchip.com>
---
 mk/toolchain/gcc/rte.vars.mk | 5 +++++
 1 file changed, 5 insertions(+)
  

On 19/06/2015 22:29, Cyril Chemparathy wrote:
> From: Cyril Chemparathy <cchemparathy@tilera.com>
>
> It is often useful to build with debug enabled, we add a config
> (CONFIG_RTE_TOOLCHAIN_DEBUG) to do so.
>
> Note: This patch does not include corresponding changes for ICC.  The
> author pleads abject ignorance in this regard, and welcomes
> recommendations. :-)
>
> Change-Id: I499e591e1b7d71df751fd40d1fdcbe6975eeeb27
> Signed-off-by: Cyril Chemparathy <cchemparathy@ezchip.com>
> ---
>   mk/toolchain/gcc/rte.vars.mk | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk
> index 0f51c66..22c4c1f 100644
> --- a/mk/toolchain/gcc/rte.vars.mk
> +++ b/mk/toolchain/gcc/rte.vars.mk
> @@ -71,6 +71,11 @@ ifeq (,$(findstring -O0,$(EXTRA_CFLAGS)))
>   endif
>   endif
>   
> +ifeq ($(CONFIG_RTE_TOOLCHAIN_DEBUG),y)
> +TOOLCHAIN_CFLAGS += -g -ggdb
> +TOOLCHAIN_LDFLAGS += -g -ggdb
> +endif
> +
>   WERROR_FLAGS := -W -Wall -Werror -Wstrict-prototypes -Wmissing-prototypes
>   WERROR_FLAGS += -Wmissing-declarations -Wold-style-definition -Wpointer-arith
>   WERROR_FLAGS += -Wcast-align -Wnested-externs -Wcast-qual
I don't think you need to modify the makefiles and introduce a new 
compile time option for this.
The same result can be easily achieved by setting EXTRA_CFLAGS in the 
command line. ie:
     $ make install T=x86_64-native-linuxapp-gcc EXTRA_CFLAGS='-g -ggdb'

Sergio
  

On 2015-06-22 09:44, Gonzalez Monroy, Sergio wrote:
> On 19/06/2015 22:29, Cyril Chemparathy wrote:
>> From: Cyril Chemparathy <cchemparathy@tilera.com>
>>
>> It is often useful to build with debug enabled, we add a config
>> (CONFIG_RTE_TOOLCHAIN_DEBUG) to do so.
>>
>>   +ifeq ($(CONFIG_RTE_TOOLCHAIN_DEBUG),y)
>> +TOOLCHAIN_CFLAGS += -g -ggdb
>> +TOOLCHAIN_LDFLAGS += -g -ggdb
>> +endif

> I don't think you need to modify the makefiles and introduce a new
> compile time option for this.
> The same result can be easily achieved by setting EXTRA_CFLAGS in the
> command line. ie:
>     $ make install T=x86_64-native-linuxapp-gcc EXTRA_CFLAGS='-g -ggdb'

Why isn't -g standard though? The binaries should/will anyhow be
stripped when used for production - but debugging information should be
useful when analysing crashes.

// Simon
  

On Mon, 22 Jun 2015 08:44:41 +0100
"Gonzalez Monroy, Sergio" <sergio.gonzalez.monroy@intel.com> wrote:

> I don't think you need to modify the makefiles and introduce a new 
> compile time option for this.
> The same result can be easily achieved by setting EXTRA_CFLAGS in the 
> command line. ie:
>      $ make install T=x86_64-native-linuxapp-gcc EXTRA_CFLAGS='-g
> -ggdb'

Fair enough.  Please ignore this patch then.  Thanks!
  

On 22/06/2015 08:56, Simon Kågström wrote:
> On 2015-06-22 09:44, Gonzalez Monroy, Sergio wrote:
>> On 19/06/2015 22:29, Cyril Chemparathy wrote:
>>> From: Cyril Chemparathy <cchemparathy@tilera.com>
>>>
>>> It is often useful to build with debug enabled, we add a config
>>> (CONFIG_RTE_TOOLCHAIN_DEBUG) to do so.
>>>
>>>    +ifeq ($(CONFIG_RTE_TOOLCHAIN_DEBUG),y)
>>> +TOOLCHAIN_CFLAGS += -g -ggdb
>>> +TOOLCHAIN_LDFLAGS += -g -ggdb
>>> +endif
>> I don't think you need to modify the makefiles and introduce a new
>> compile time option for this.
>> The same result can be easily achieved by setting EXTRA_CFLAGS in the
>> command line. ie:
>>      $ make install T=x86_64-native-linuxapp-gcc EXTRA_CFLAGS='-g -ggdb'
> Why isn't -g standard though? The binaries should/will anyhow be
> stripped when used for production - but debugging information should be
> useful when analysing crashes.
I guess you could argue that, to always build with debug info then strip 
it down.
You would need another flag to strip debug info for production, or leave 
it for debugging.

In my opinion is not worth it, but it you feel strongly about it you can 
submit patches and
let the community decide.

Sergio
> // Simon
>
  

2015-06-23 08:39, Gonzalez Monroy, Sergio:
> On 22/06/2015 08:56, Simon Kågström wrote:
> > On 2015-06-22 09:44, Gonzalez Monroy, Sergio wrote:
> >> On 19/06/2015 22:29, Cyril Chemparathy wrote:
> >>> From: Cyril Chemparathy <cchemparathy@tilera.com>
> >>>
> >>> It is often useful to build with debug enabled, we add a config
> >>> (CONFIG_RTE_TOOLCHAIN_DEBUG) to do so.
> >>>
> >>>    +ifeq ($(CONFIG_RTE_TOOLCHAIN_DEBUG),y)
> >>> +TOOLCHAIN_CFLAGS += -g -ggdb
> >>> +TOOLCHAIN_LDFLAGS += -g -ggdb
> >>> +endif
> >> I don't think you need to modify the makefiles and introduce a new
> >> compile time option for this.
> >> The same result can be easily achieved by setting EXTRA_CFLAGS in the
> >> command line. ie:
> >>      $ make install T=x86_64-native-linuxapp-gcc EXTRA_CFLAGS='-g -ggdb'
> > Why isn't -g standard though? The binaries should/will anyhow be
> > stripped when used for production - but debugging information should be
> > useful when analysing crashes.
> 
> I guess you could argue that, to always build with debug info then strip 
> it down.
> You would need another flag to strip debug info for production, or leave 
> it for debugging.
> 
> In my opinion is not worth it, but it you feel strongly about it you can 
> submit patches and
> let the community decide.

I think stripping is a packaging responsibility.
It would be a good idea to always provide debugging symbols.
  

On 2015-06-23 09:47, Thomas Monjalon wrote:
> 2015-06-23 08:39, Gonzalez Monroy, Sergio:
>> I guess you could argue that, to always build with debug info then strip 
>> it down.
>> You would need another flag to strip debug info for production, or leave 
>> it for debugging.
>>
>> In my opinion is not worth it, but it you feel strongly about it you can 
>> submit patches and
>> let the community decide.
> 
> I think stripping is a packaging responsibility.
> It would be a good idea to always provide debugging symbols.

Yes, I think this would be the best way too, and should be pretty much
standard procedure.

DPDK is anyhow just a library - stripping should be up to the
application / packaging to do.

// Simon