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⇱ Linux 6.18 Kbuild Brings An Optimization For gen_init_cpio On Btrfs Or XFS - Phoronix


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Linux 6.18 Kbuild Brings An Optimization For gen_init_cpio On Btrfs Or XFS

Written by Michael Larabel in Linux Kernel on 2 October 2025 at 09:17 AM EDT. Add A Comment
The Kbuild changes have been merged for the in-development Linux 6.18 kernel.

The Kbuild pull for Linux 6.18 is the first under new maintainership and brings a few changes worth calling out.

First up, the minimum supported LLVM/Clang compiler version to build the Linux kernel has been increased to LLVM 15.0. This is a reasonable new minimum version with LLVM/Clang 15 having come out in September 2022 and most using Clang to build the Linux kernel tend to be more on the leading-edge.

The Kbuild changes for the Linux 6.18 kernel also unify and consolidate all the CONFIG_WERROR / W=e handling for promoting compiler warnings to errors. Those options are also now respected when building the user-space programs living within the Linux kernel tree.

The Kbuild changes also include support for copy_file_range() and data segment alignment in gen_init_cpio for improving performance on file-systems with reflinks like Btrfs and XFS. The gen_init_cpio tool for building a CPIO archive for a root file-system image and will now enjoy better performance on the likes of Btrfs and XFS. The patch explains:
"Add filename zero-padding logic to gen_init_cpio, which can be triggered via the new -a

More details on these Kbuild changes for Linux 6.18 via this pull.

Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via MichaelLarabel.com.