1 #!/bin/sh
2 # SPDX-License-Identifier: 0BSD
3 #
4 # This is a wrapper for xz to compress the ker
5 # compression options depending on the archite
6 #
7 # Author: Lasse Collin <lasse.collin@tukaani.or
8
9 # This has specialized settings for the follow
10 # XZ-compressed kernel isn't currently support
11 #
12 # Arch Align Notes
13 # arm 2/4 ARM and ARM-Thumb2
14 # arm64 4
15 # csky 2
16 # loongarch 4
17 # mips 2/4 MicroMIPS is 2-byte al
18 # parisc 4
19 # powerpc 4 Uses its own wrapper f
20 # riscv 2/4
21 # s390 2
22 # sh 2
23 # sparc 4
24 # x86 1
25
26 # A few archs use 2-byte or 4-byte aligned ins
27 # the kernel config. This function is used to
28 # config option is set to "y".
29 is_enabled()
30 {
31 grep -q "^$1=y$" include/config/auto.c
32 }
33
34 # XZ_VERSION is needed to disable features tha
35 # old XZ Utils versions.
36 XZ_VERSION=$($XZ --robot --version) || exit
37 XZ_VERSION=$(printf '%s\n' "$XZ_VERSION" | sed
38
39 # Assume that no BCJ filter is available.
40 BCJ=
41
42 # Set the instruction alignment to 1, 2, or 4
43 #
44 # Set the BCJ filter if one is available.
45 # It must match the #ifdef usage in lib/decomp
46 case $SRCARCH in
47 arm)
48 if is_enabled CONFIG_THUMB2_KE
49 ALIGN=2
50 BCJ=--armthumb
51 else
52 ALIGN=4
53 BCJ=--arm
54 fi
55 ;;
56
57 arm64)
58 ALIGN=4
59
60 # ARM64 filter was added in XZ
61 if [ "$XZ_VERSION" -ge 5004000
62 BCJ=--arm64
63 else
64 echo "$0: Upgrading to
65 "would enable
66 "for better co
67 fi
68 ;;
69
70 csky)
71 ALIGN=2
72 ;;
73
74 loongarch)
75 ALIGN=4
76 ;;
77
78 mips)
79 if is_enabled CONFIG_CPU_MICRO
80 ALIGN=2
81 else
82 ALIGN=4
83 fi
84 ;;
85
86 parisc)
87 ALIGN=4
88 ;;
89
90 powerpc)
91 ALIGN=4
92
93 # The filter is only for big e
94 if is_enabled CONFIG_CPU_BIG_E
95 BCJ=--powerpc
96 fi
97 ;;
98
99 riscv)
100 if is_enabled CONFIG_RISCV_ISA
101 ALIGN=2
102 else
103 ALIGN=4
104 fi
105
106 # RISC-V filter was added in X
107 if [ "$XZ_VERSION" -ge 5006000
108 BCJ=--riscv
109 else
110 echo "$0: Upgrading to
111 "would enable
112 "for better co
113 fi
114 ;;
115
116 s390)
117 ALIGN=2
118 ;;
119
120 sh)
121 ALIGN=2
122 ;;
123
124 sparc)
125 ALIGN=4
126 BCJ=--sparc
127 ;;
128
129 x86)
130 ALIGN=1
131 BCJ=--x86
132 ;;
133
134 *)
135 echo "$0: Arch-specific tuning
136
137 # Guess 2-byte-aligned instruc
138 # should hurt less than guessi
139 ALIGN=2
140 ;;
141 esac
142
143 # Select the LZMA2 options matching the instru
144 case $ALIGN in
145 1) LZMA2OPTS= ;;
146 2) LZMA2OPTS=lp=1 ;;
147 4) LZMA2OPTS=lp=2,lc=2 ;;
148 *) echo "$0: ALIGN wrong or missing"
149 esac
150
151 # Use single-threaded mode because it compress
152 # (and uses less RAM) than multithreaded mode.
153 #
154 # For the best compression, the dictionary siz
155 # smaller than the uncompressed kernel. 128 Mi
156 # needs less than 1400 MiB of RAM in single-th
157 #
158 # On the archs that use this script to compres
159 # decompression in the preboot code is done in
160 # Thus the dictionary size doesn't affect the
161 # of the preboot decompressor at all.
162 exec $XZ --check=crc32 --threads=1 $BCJ --lzma
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