Zack's Kernel News

Zack's Kernel News

Article from Issue 242/2021
Author(s):

This month in Kernel News: Dealing with Older GCC Versions; and On-boarding New Kernel Hackers.

Dealing with Older GCC Versions

This past year, Linus Torvalds upped the supported version of GCC to version 4.9 or newer. The idea is that it's good to support older as well as newer versions, because then people running on old systems can still compile the kernel. At the same time, if no one in the world is using a particular older compiler, you might be able to simplify some kernel code by removing support for that compiler. So there's not only an incentive for the kernel developers to support older compilers, there's also an incentive for them to abandon very old compilers when they can safely get away with it.

It's an ever-advancing debate. Recently for example, Thomas Gleixner threw up his hands in disgust at some compiler behavior. Arnd Bergmann had posted some kernel patches to work around some ugly compiler behavior in GCC 4.9 that wasn't necessary in GCC 5 and newer.

Specifically, Arnd's code added some symbol references that were never actually used in the code. The symbols were then also referenced in unused inline functions, so as not to trigger a warning. Then, as Thomas pointed out, the symbols and the inline functions were all optimized out of the final compiled binary.

[...]

Use Express-Checkout link below to read the full article (PDF).

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Security Lessons: Rescue Tools

    When attackers strike your system, you need to determine exactly what damage has been done. Here are some tools to help.

  • Kernel News

    Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.

  • Kernel News

    This month in Kernel News: Shared Processes with Hyper-Threading; Cleaning Up printk(); and Rust in the Kernel.

  • Kernel Protection

    Security vulnerabilities in the kernel often remain undetected. The kernel hacker initiative, Kernel Self-Protection, promotes safe programming techniques to keep attackers off the network, and, if they do slip through the net, mitigate the consequences.

  • Kernel News

    Chronicler Zack Brown reports on the NOVA filesystem, making system calls userspace only, and extending module support to plain executables. 

comments powered by Disqus

Direct Download

Read full article as PDF:

Price $2.95

News