firmware: Add support for loading compressed files
This patch adds the support for loading compressed firmware files.
The primary motivation is to reduce the storage size; e.g. currently
the files in /lib/firmware on my machine counts up to 419MB, while
they can be reduced to 130MB by file compression.
The patch introduces a new kconfig option CONFIG_FW_LOADER_COMPRESS.
Even with this option set, the firmware loader still tries to load the
original firmware file as-is at first, but then falls back to the file
with ".xz" extension when it's not found, and the decompressed file
content is returned to the caller of request_firmware(). So, no
change is needed for the rest.
Currently only XZ format is supported. A caveat is that the kernel XZ
helper code supports only CRC32 (or none) integrity check type, so
you'll have to compress the files via xz -C crc32 option.
Since we can't determine the expanded size immediately, the patch
re-uses the paged buffer that was used for the user-mode fallback, and
puts the decompressed content page by page as well as a new kconfig for
enabling the paged buffer support.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
3 files changed
