Re: [Xen-devel] [PATCH v3] tools: detect appropriate debug optimization level

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On 3/2/18 6:46 AM, Wei Liu wrote:
> On Fri, Feb 23, 2018 at 11:26:17PM -0600, Doug Goldstein wrote:
>> On 4/28/16 12:40 PM, Wei Liu wrote:
>>> On Tue, Apr 26, 2016 at 09:38:45AM -0500, Doug Goldstein wrote:
>>>> When building debug use -Og as the optimization level if its available,
>>>> otherwise retain the use of -O0. -Og has been added by GCC to enable all
>>>> optimizations that to not affect debugging while retaining full
>>>> debugability.
>>>>
>>>> Signed-off-by: Doug Goldstein <cardoe@xxxxxxxxxx>
>>>> ---
>>>> change since v2:
>>>> - switch back to cc-option-add to not call cc-option on every invocation
>>>> change since v1:
>>>> - switch to cc-option to only specify -O0 if -Og isn't supported
>>>> ---
>>>>  tools/Rules.mk | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/tools/Rules.mk b/tools/Rules.mk
>>>> index 9ef0b47..1b79a6e 100644
>>>> --- a/tools/Rules.mk
>>>> +++ b/tools/Rules.mk
>>>> @@ -138,6 +138,7 @@ SHLIB_libxenvchan  = $(SHDEPS_libxenvchan) 
>>>> -Wl,-rpath-link=$(XEN_LIBVCHAN)
>>>>  ifeq ($(debug),y)
>>>>  # Disable optimizations and enable debugging information for macros
>>>>  CFLAGS += -O0 -g3
>>>> +$(call cc-option-add,CFLAGS,CC,-Og)
> 
> Though -Og will supersede -O0 because it comes later, I would rather you
> use cc-option to selectively add one of the two, like:
> 
> CFLAGS += $(cc-option,CC,-Og,-O0)
> 
> Wei.
> 

Wei,

It was like that in v2 but I changed it per Ian's request to this
version. See:
https://lists.xenproject.org/archives/html/xen-devel/2016-04/msg02822.html
for reference.

-- 
Doug Goldstein

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