Zstd Compressed Firmware Will Finally Be Supported With Linux 5.19

For two years there has been interest and unmerged patches for allowing Linux's plethora of firmware blobs to be Zstd-compressed for helping to save disk space. Finally it looks like for Linux 5.19 that optional Zstd firmware compression support will be merged.

The Linux kernel continues making greater use of the Facebook-developed Zstandard compression algorithm thanks in large part to its very speed decompression performance and other modern features. From transparent file-system compression to compressing the kernel image with Zstd, there is growing use of it within the kernel. Talked about every so often Zstd firmware compression support. Compressing the Linux firmware tree with Zstd has tended to be slightly larger than using the existing XZ support, but the decompression when loading the firmware files is much faster.

Finally for Linux 5.19 it looks like that Zstd firmware compression handling code will be merged. Greg Kroah-Hartman has queued it up into driver-core-next as of this past weekend. The Zstd-compressed firmware infrastructure as well as the self-tests are all queued up in driver-core-next ahead of the Linux 5.19 merge window opening around the end of May.

Zstd firmware compression support finally landed in driver-core-next, meaning it should in turn be submitted for Linux 5.19 barring any last minute issues.

This support splits the existing FW_LOADER_COMPRESS to be a general knob now with the XZ firmware compression moved to a new knob of FW_LOADER_COMPRESS_XZ while adding FW_LOADER_COMPRESS_ZSTD to enable this Zstd-compressed firmware file support. Zstd-compressed firmware files will be automatically loaded when the kernel support is enabled and the firmware file ends in .zst.