Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
Retpoline support in GCC 5?
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Other Things Gentoo
View previous topic :: View next topic  
Author Message
bark
n00b
n00b


Joined: 26 Mar 2018
Posts: 3

PostPosted: Mon Mar 26, 2018 7:39 pm    Post subject: Retpoline support in GCC 5? Reply with quote

Does the Gentoo Project have any plans to backport retpoline to GCC 5.4.0-r* ??
_________________
Be liberal in what you accept, and conservative in what you send. -Jon Postel
Back to top
View user's profile Send private message
John R. Graham
Administrator
Administrator


Joined: 08 Mar 2005
Posts: 9868
Location: Somewhere over Atlanta, Georgia

PostPosted: Mon Mar 26, 2018 7:59 pm    Post subject: Reply with quote

You can ask the Toolchain Project at toolchain@gentoo.org, but I kind of doubt it. What's your specific need?

- John
_________________
I can confirm that I have received between 0 and 499 National Security Letters.
Back to top
View user's profile Send private message
fedeliallalinea
Bodhisattva
Bodhisattva


Joined: 08 Mar 2003
Posts: 18564
Location: here

PostPosted: Mon Mar 26, 2018 8:07 pm    Post subject: Reply with quote

I doubt, also for gcc 6.x
_________________
Questions are guaranteed in life; Answers aren't.
Back to top
View user's profile Send private message
bark
n00b
n00b


Joined: 26 Mar 2018
Posts: 3

PostPosted: Mon Mar 26, 2018 8:08 pm    Post subject: Reply with quote

John R. Graham wrote:
You can ask the Toolchain Project at toolchain@gentoo.org, but I kind of doubt it. What's your specific need?

- John


Specific need is that I'm still building the kernel with GCC 5.4.0-r3.

This page seems to indicate that 5.4 and above are supported currently by Toolchain.

I was hoping that would mean it's going to receive support for retpoline, but I haven't seen anything definitive.
_________________
Be liberal in what you accept, and conservative in what you send. -Jon Postel
Back to top
View user's profile Send private message
mike155
Guru
Guru


Joined: 17 Sep 2010
Posts: 453
Location: Frankfurt, Germany

PostPosted: Mon Mar 26, 2018 9:17 pm    Post subject: Reply with quote

Look here for a backport of Spectre patches to GCC 5.5.
Back to top
View user's profile Send private message
bark
n00b
n00b


Joined: 26 Mar 2018
Posts: 3

PostPosted: Mon Mar 26, 2018 9:49 pm    Post subject: Reply with quote

mike155 wrote:
Look here for a backport of Spectre patches to GCC 5.5.


Thanks!

I see that retpoline support was added to that branch.

Is it just a matter of coaxing Toolchain to pull in those patches?
_________________
Be liberal in what you accept, and conservative in what you send. -Jon Postel
Back to top
View user's profile Send private message
mike155
Guru
Guru


Joined: 17 Sep 2010
Posts: 453
Location: Frankfurt, Germany

PostPosted: Mon Mar 26, 2018 11:20 pm    Post subject: Reply with quote

As far as I can see, there won't be Gentoo support for Spectre patches in GCC 5. GCC 5 is masked already. The current / stable version of GCC in Gentoo is GCC 6. GCC 7.3 is available and Spectre patches are included in this version.

It's time to update to GCC 7.3!

If you really want/need to stay with GCC 5 ...

1) Install GCC 7.3 additionally to GCC 5. GCC is slotted, and it's perfectly fine to have two different GCC compilers on a machine. You can switch between the GCC versions using gcc-config.

2) Alternatively, you could set up a second Linux server with GCC 7.3. Build your kernel on the second server and copy it to your original machine.

3) Alternatively, you could build GCC 5.5 and apply the Spectre patches yourself. I wouldn't recommend that - unless you are very experienced with Gentoo and GCC.
Back to top
View user's profile Send private message
Naib
Watchman
Watchman


Joined: 21 May 2004
Posts: 5279
Location: Removed by Neddy

PostPosted: Mon Mar 26, 2018 11:28 pm    Post subject: Reply with quote

whats holding you back at GCC-5.x ?
_________________
The best argument against democracy is a five-minute conversation with the average voter
Great Britain is a republic, with a hereditary president, while the United States is a monarchy with an elective king
Back to top
View user's profile Send private message
Hu
Moderator
Moderator


Joined: 06 Mar 2007
Posts: 12240

PostPosted: Tue Mar 27, 2018 1:32 am    Post subject: Reply with quote

bark wrote:
John R. Graham wrote:
You can ask the Toolchain Project at toolchain@gentoo.org, but I kind of doubt it. What's your specific need?
Specific need is that I'm still building the kernel with GCC 5.4.0-r3.
You can continue to use gcc 5.4 for your kernel. You will not receive the benefit of the full retpoline patches if you use gcc-5, but the resulting kernel should compile correctly and run correctly. If your use case requires a kernel with maximum anti-Spectre protection, you need to upgrade to a newer gcc. If you only care about using a modern kernel for the other improvements that are added over time, and you do not mind having less than full anti-Spectre, you can continue to use gcc-5 for your kernel.
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Other Things Gentoo All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum