[PATCH 04/17] x86: Remove support for BZIP2 and LZMA compressed kernel

From: Adam Borowski <hidden>
Date: 2018-11-09 19:05:14
Also in: linux-mips, linux-s390, linux-sh, lkml
Reply to: Adam Borowski, 2018-11-09

While bzip2 used to be good in its heyday, it's been drastically eclipsed
by newer algorithms.  In no case it's a rational choice anymore -- at any
point of the size-to-compression curve, there's something much better.
As we control the build process, any .configs that still select it will
harmlessly be adjusted, thus there's no risk of breakage.

Bare lzma is redundant with xz, lacks some improvements, and uses its own
copy of code instead using the common library.

Signed-off-by: Adam Borowski <redacted>
---
 Documentation/x86/boot.txt        | 11 +++++------
 arch/x86/Kconfig                  |  2 --
 arch/x86/boot/compressed/Makefile | 12 +++---------
 arch/x86/boot/compressed/misc.c   |  8 --------
 arch/x86/include/asm/boot.h       |  4 +---
 5 files changed, 9 insertions(+), 28 deletions(-)

diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index a47b6bae3356..fbd9720989e5 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt

@@ -682,12 +682,11 @@ Protocol:	2.08+
   of the protected-mode code to the payload.
 
   The payload may be compressed. The format of both the compressed and
-  uncompressed data should be determined using the standard magic
-  numbers.  The currently supported compression formats are gzip
-  (magic numbers 1F 8B or 1F 9E), bzip2 (magic number 42 5A), LZMA
-  (magic number 5D 00), XZ (magic number FD 37), LZ4 (magic number
-  02 21) and ZSTD (magic number 28 B5). The uncompressed payload is
-  currently always ELF (magic number 7F 45 4C 46).
+  uncompressed data should be determined using the standard magic numbers.
+  The currently supported compression formats are gzip (magic numbers 1F 8B
+  or 1F 9E), XZ (magic number FD 37), LZ4 (magic number 02 21) and ZSTD
+  (magic number 28 B5). The uncompressed payload is currently always ELF
+  (magic number 7F 45 4C 46).
 
 Field name:	payload_length
 Type:		read

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 203f7467f5c4..a47af31bbc62 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig

@@ -158,10 +158,8 @@ config X86
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64
 	select HAVE_IRQ_TIME_ACCOUNTING
-	select HAVE_KERNEL_BZIP2
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZ4
-	select HAVE_KERNEL_LZMA
 	select HAVE_KERNEL_LZO
 	select HAVE_KERNEL_XZ
 	select HAVE_KERNEL_ZSTD

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 6d2a8d2d378d..763aeb850658 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile

@@ -7,13 +7,13 @@
 # vmlinuz is:
 #	decompression code (*.o)
 #	asm globals (piggy.S), including:
-#		vmlinux.bin.(gz|bz2|lzma|...)
+#		vmlinux.bin.(gz|zst|xz|...)
 #
 # vmlinux.bin is:
 #	vmlinux stripped of debugging and comments
 # vmlinux.bin.all is:
 #	vmlinux.bin + vmlinux.relocs
-# vmlinux.bin.(gz|bz2|lzma|...) is:
+# vmlinux.bin.(gz|zst|xz|...) is:
 #	(see scripts/Makefile.lib size_append)
 #	compressed vmlinux.bin.all + u32 size of vmlinux.bin.all

@@ -23,7 +23,7 @@ OBJECT_FILES_NON_STANDARD	:= y
 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
 KCOV_INSTRUMENT		:= n
 
-targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
+targets := vmlinux vmlinux.bin vmlinux.bin.gz \
 	vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4 vmlinux.bin.zst
 
 KBUILD_CFLAGS := -m$(BITS) -O2

@@ -132,10 +132,6 @@ vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs
 
 $(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
 	$(call if_changed,gzip)
-$(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE
-	$(call if_changed,bzip2)
-$(obj)/vmlinux.bin.lzma: $(vmlinux.bin.all-y) FORCE
-	$(call if_changed,lzma)
 $(obj)/vmlinux.bin.xz: $(vmlinux.bin.all-y) FORCE
 	$(call if_changed,xzkern)
 $(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) FORCE

@@ -146,8 +142,6 @@ $(obj)/vmlinux.bin.zst: $(vmlinux.bin.all-y) FORCE
 	$(call if_changed,zstd)
 
 suffix-$(CONFIG_KERNEL_GZIP)	:= gz
-suffix-$(CONFIG_KERNEL_BZIP2)	:= bz2
-suffix-$(CONFIG_KERNEL_LZMA)	:= lzma
 suffix-$(CONFIG_KERNEL_XZ)	:= xz
 suffix-$(CONFIG_KERNEL_LZO) 	:= lzo
 suffix-$(CONFIG_KERNEL_LZ4) 	:= lz4

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b6c8921100fb..c0d75b74f199 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c

@@ -57,14 +57,6 @@ static int lines, cols;
 #include "../../../../lib/decompress_inflate.c"
 #endif
 
-#ifdef CONFIG_KERNEL_BZIP2
-#include "../../../../lib/decompress_bunzip2.c"
-#endif
-
-#ifdef CONFIG_KERNEL_LZMA
-#include "../../../../lib/decompress_unlzma.c"
-#endif
-
 #ifdef CONFIG_KERNEL_XZ
 #include "../../../../lib/decompress_unxz.c"
 #endif

diff --git a/arch/x86/include/asm/boot.h b/arch/x86/include/asm/boot.h
index d6dd43d25d9f..afbf3d60f22e 100644
--- a/arch/x86/include/asm/boot.h
+++ b/arch/x86/include/asm/boot.h

@@ -24,9 +24,7 @@
 # error "Invalid value for CONFIG_PHYSICAL_ALIGN"
 #endif
 
-#if defined(CONFIG_KERNEL_BZIP2)
-# define BOOT_HEAP_SIZE		0x400000
-#elif defined(CONFIG_KERNEL_ZSTD)
+#if defined(CONFIG_KERNEL_ZSTD)
 # define BOOT_HEAP_SIZE		 0x30000
 #else
 # define BOOT_HEAP_SIZE		 0x10000

-- 
2.19.1

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