[PSA] Minor Compiler Upgrade (GCC 4.9.1 -> GCC 4.9.2)

[Caroline Tice]

TL; DR: In order to obtain several important bug fixes, we are doing to do a minor upgrade of ChromiumOS GCC to 4.9.2 today (Feb. 27).  The upgrade should take effect by tomorrow morning. 

This change is expected to be transparent to developers, with the change being tested by the SDK bots before its rolled out to developers. 

We have done both performance and correctness testing, including kernel testing. 

The following CL will make this happen - 

    Update chromiumos gcc to gcc 4.9.2

       -https://chromium-review.googlesource.com/#/c/246732/

 

This is a minor/bug-fix upgrade.  Overall performance, as measured by telemetry benchmarks, is the same as with GCC 4.9.1 for the intel boards and it seems to be slightly better for the arm boards.

Please report issues in crosbug, with the label Build-Toolchain and/or send email to chromeos-...@google.com.

Thanks,

Caroline Tice, Luis Lozano and The Chromeos Toolchain Team