An question about default opened option "-fstack-protector-strong"

[Shao, Ting]

Dear Robie,

Thank you for your help, that's very useful for me. :)

Regards,
Shaoting

-----Original Message-----
From: Robie Basak [mailto:robie.basak at ubuntu.com] 
Sent: Sunday, June 17, 2018 2:47 AM
To: Shao, Ting <ting.shao at intel.com>
Cc: ubuntu-devel-discuss at lists.ubuntu.com
Subject: Re: An question about default opened option "-fstack-protector-strong"

Hi Shaoting,

On Thu, Jun 14, 2018 at 07:03:28AM +0000, Shao, Ting wrote:
> 1.      I installed gcc from apt-get by default, is Ubuntu providing a customized version of GCC?

Yes. I don't think Ubuntu is unique at all amongst distributions in this regard.

> 2.      If answer of 1 is yes, then you may have a repo that host the customized GCC code, if I am right, could you please show me where I can find the proof of that customization?

You can find the source for every published Ubuntu package on Launchpad.
For example:
https://launchpad.net/ubuntu/+source/gcc-5/5.4.0-6ubuntu1~16.04.9

There's an experimental git view you might find easier to use:

https://git.launchpad.net/ubuntu/+source/gcc-5/log/?h=applied/ubuntu/xenial-devel

Note that in the case of gcc-5, there are an extensive set of patches that are dynamically applied to the tree before the package is built.
This is driven from debian/rules.patch via debian/rules. The patches appear to be in debian/patches/ but I think they're selectively added, so you'll need to do some digging to understand exactly what applies in your case. Launchpad also stores build logs, available through the first link above, if that helps you match things up.

Hope that helps,

Robie