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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-03 16:03:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-03 16:03:23 -0700
commitc0dfadfed87489fa6126ece161a14c2d15dbdc79 (patch)
tree2b1ac3fb464e4d18b57e3d4735cd6b60454cc972 /scripts
parentba77c568f3160657a5f7905289c07d18c2dfde78 (diff)
parent1ac1efa5f6950f8f126f2c1921bb699ce009ec7d (diff)
Merge tag 'x86-boot-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot updates from Ingo Molnar: "The main change in this cycle was to add support for ZSTD-compressed kernel and initrd images. ZSTD has a very fast decompressor, yet it compresses better than gzip" * tag 'x86-boot-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: Documentation: dontdiff: Add zstd compressed files .gitignore: Add ZSTD-compressed files x86: Add support for ZSTD compressed kernel x86: Bump ZO_z_extra_bytes margin for zstd usr: Add support for zstd compressed initramfs init: Add support for zstd compressed kernel lib: Add zstd support to decompress lib: Prepare zstd for preboot environment, improve performance
Diffstat (limited to 'scripts')
-rw-r--r--scripts/Makefile.lib22
1 files changed, 22 insertions, 0 deletions
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 916b2f7f7098..54f7b7eb580b 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -413,6 +413,28 @@ quiet_cmd_xzkern = XZKERN $@
quiet_cmd_xzmisc = XZMISC $@
cmd_xzmisc = cat $(real-prereqs) | $(XZ) --check=crc32 --lzma2=dict=1MiB > $@
+# ZSTD
+# ---------------------------------------------------------------------------
+# Appends the uncompressed size of the data using size_append. The .zst
+# format has the size information available at the beginning of the file too,
+# but it's in a more complex format and it's good to avoid changing the part
+# of the boot code that reads the uncompressed size.
+#
+# Note that the bytes added by size_append will make the zstd tool think that
+# the file is corrupt. This is expected.
+#
+# zstd uses a maximum window size of 8 MB. zstd22 uses a maximum window size of
+# 128 MB. zstd22 is used for kernel compression because it is decompressed in a
+# single pass, so zstd doesn't need to allocate a window buffer. When streaming
+# decompression is used, like initramfs decompression, zstd22 should likely not
+# be used because it would require zstd to allocate a 128 MB buffer.
+
+quiet_cmd_zstd = ZSTD $@
+ cmd_zstd = { cat $(real-prereqs) | $(ZSTD) -19; $(size_append); } > $@
+
+quiet_cmd_zstd22 = ZSTD22 $@
+ cmd_zstd22 = { cat $(real-prereqs) | $(ZSTD) -22 --ultra; $(size_append); } > $@
+
# ASM offsets
# ---------------------------------------------------------------------------