From e5456bdf14cb7f40b5d0a5c5e3eba59a09377f96 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sun, 31 May 2020 11:12:41 +0200
Subject: [PATCH] build: backport kernel debuginfo ZSTD compression

---
 patches/openwrt/0010-tools-add-zstd.patch     | 113 ++++++++++++++++++
 ...compress-kernel-debuginfo-using-zstd.patch |  43 +++++++
 2 files changed, 156 insertions(+)
 create mode 100644 patches/openwrt/0010-tools-add-zstd.patch
 create mode 100644 patches/openwrt/0011-build-compress-kernel-debuginfo-using-zstd.patch

diff --git a/patches/openwrt/0010-tools-add-zstd.patch b/patches/openwrt/0010-tools-add-zstd.patch
new file mode 100644
index 000000000..7862dce77
--- /dev/null
+++ b/patches/openwrt/0010-tools-add-zstd.patch
@@ -0,0 +1,113 @@
+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 13 May 2020 20:22:12 +0200
+Subject: tools: add zstd
+
+Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
+(cherry picked from commit 258dc0d0fd3aae47add9b7dca40848a92d03a4ea)
+
+diff --git a/tools/Makefile b/tools/Makefile
+index d7207ba89dd91df558eaf970961fdef225aa1f37..14fe4fb4b5f4e0c745cb8592a39bcf238dcc5444 100644
+--- a/tools/Makefile
++++ b/tools/Makefile
+@@ -33,7 +33,7 @@ tools-$(CONFIG_TARGET_mxs) += elftosb sdimage
+ tools-$(CONFIG_TARGET_ar71xx) += lzma-old
+ tools-$(CONFIG_TARGET_ar71xx)$(CONFIG_TARGET_ath79) += squashfs
+ tools-$(CONFIG_USES_MINOR) += kernel2minor
+-tools-y += lzma squashfskit4 zip
++tools-y += lzma squashfskit4 zip zstd
+ tools-$(BUILD_B43_TOOLS) += b43-tools
+ tools-$(BUILD_ISL) += isl
+ tools-$(CONFIG_USE_SPARSE) += sparse
+diff --git a/tools/zstd/Makefile b/tools/zstd/Makefile
+new file mode 100644
+index 0000000000000000000000000000000000000000..7459725e8e79b846ed96551753d07fdd02459598
+--- /dev/null
++++ b/tools/zstd/Makefile
+@@ -0,0 +1,20 @@
++include $(TOPDIR)/rules.mk
++
++PKG_NAME:=zstd
++PKG_VERSION:=1.4.4
++
++PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
++PKG_SOURCE_URL:=@GITHUB/facebook/zstd/releases/download/v$(PKG_VERSION)
++PKG_HASH:=a364f5162c7d1a455cc915e8e3cf5f4bd8b75d09bc0f53965b0c9ca1383c52c8
++
++PKG_LICENSE:=BSD-3-Clause
++PKG_LICENSE_FILES:=LICENSE
++PKG_CPE_ID:=cpe:/a:facebook:zstandard
++
++HOST_BUILD_PARALLEL:=1
++
++include $(INCLUDE_DIR)/host-build.mk
++
++HOST_MAKE_FLAGS = PREFIX=$(HOST_BUILD_PREFIX) HAVE_ZLIB=0 HAVE_LZMA=0 HAVE_LZ4=0
++
++$(eval $(call HostBuild))
+diff --git a/tools/zstd/patches/0001-build-issue-More-portable-header-prefix-usage-1987.patch b/tools/zstd/patches/0001-build-issue-More-portable-header-prefix-usage-1987.patch
+new file mode 100644
+index 0000000000000000000000000000000000000000..6d743aa3855262c2a0956f70ec99588ce9ebe53b
+--- /dev/null
++++ b/tools/zstd/patches/0001-build-issue-More-portable-header-prefix-usage-1987.patch
+@@ -0,0 +1,61 @@
++From 06a57cf57e3c4e887cadcf688e3081154f3f6db4 Mon Sep 17 00:00:00 2001
++Message-Id: <06a57cf57e3c4e887cadcf688e3081154f3f6db4.1589392463.git.mschiffer@universe-factory.net>
++From: Bimba Shrestha <bimbashrestha@fb.com>
++Date: Thu, 6 Feb 2020 14:10:51 -0800
++Subject: [PATCH] [build-issue] More portable header prefix usage (#) (#1987)
++
++* make 4.3 build issue fix
++
++* Changing header name and adding comment
++---
++ programs/Makefile | 11 +++++++----
++ 1 file changed, 7 insertions(+), 4 deletions(-)
++
++diff --git a/programs/Makefile b/programs/Makefile
++index b75314a83f43..a9ee3cb5311b 100644
++--- a/programs/Makefile
+++++ b/programs/Makefile
++@@ -94,9 +94,12 @@ endif
++ 
++ VOID = /dev/null
++ 
+++# Make 4.3 doesn't support '\#' anymore (https://lwn.net/Articles/810071/)
+++NUM_SYMBOL := \#
+++
++ # thread detection
++ NO_THREAD_MSG := ==> no threads, building without multithreading support
++-HAVE_PTHREAD := $(shell printf '\#include <pthread.h>\nint main(void) { return 0; }' > have_pthread.c && $(CC) $(FLAGS) -o have_pthread$(EXT) have_pthread.c -pthread 2> $(VOID) && rm have_pthread$(EXT) && echo 1 || echo 0; rm have_pthread.c)
+++HAVE_PTHREAD := $(shell printf '$(NUM_SYMBOL)include <pthread.h>\nint main(void) { return 0; }' > have_pthread.c && $(CC) $(FLAGS) -o have_pthread$(EXT) have_pthread.c -pthread 2> $(VOID) && rm have_pthread$(EXT) && echo 1 || echo 0; rm have_pthread.c)
++ HAVE_THREAD := $(shell [ "$(HAVE_PTHREAD)" -eq "1" -o -n "$(filter Windows%,$(OS))" ] && echo 1 || echo 0)
++ ifeq ($(HAVE_THREAD), 1)
++ THREAD_MSG := ==> building with threading support
++@@ -108,7 +111,7 @@ endif
++ 
++ # zlib detection
++ NO_ZLIB_MSG := ==> no zlib, building zstd without .gz support
++-HAVE_ZLIB := $(shell printf '\#include <zlib.h>\nint main(void) { return 0; }' > have_zlib.c && $(CC) $(FLAGS) -o have_zlib$(EXT) have_zlib.c -lz 2> $(VOID) && rm have_zlib$(EXT) && echo 1 || echo 0; rm have_zlib.c)
+++HAVE_ZLIB := $(shell printf '$(NUM_SYMBOL)include <zlib.h>\nint main(void) { return 0; }' > have_zlib.c && $(CC) $(FLAGS) -o have_zlib$(EXT) have_zlib.c -lz 2> $(VOID) && rm have_zlib$(EXT) && echo 1 || echo 0; rm have_zlib.c)
++ ifeq ($(HAVE_ZLIB), 1)
++ ZLIB_MSG := ==> building zstd with .gz compression support
++ ZLIBCPP = -DZSTD_GZCOMPRESS -DZSTD_GZDECOMPRESS
++@@ -119,7 +122,7 @@ endif
++ 
++ # lzma detection
++ NO_LZMA_MSG := ==> no liblzma, building zstd without .xz/.lzma support
++-HAVE_LZMA := $(shell printf '\#include <lzma.h>\nint main(void) { return 0; }' > have_lzma.c && $(CC) $(FLAGS) -o have_lzma$(EXT) have_lzma.c -llzma 2> $(VOID) && rm have_lzma$(EXT) && echo 1 || echo 0; rm have_lzma.c)
+++HAVE_LZMA := $(shell printf '$(NUM_SYMBOL)include <lzma.h>\nint main(void) { return 0; }' > have_lzma.c && $(CC) $(FLAGS) -o have_lzma$(EXT) have_lzma.c -llzma 2> $(VOID) && rm have_lzma$(EXT) && echo 1 || echo 0; rm have_lzma.c)
++ ifeq ($(HAVE_LZMA), 1)
++ LZMA_MSG := ==> building zstd with .xz/.lzma compression support
++ LZMACPP = -DZSTD_LZMACOMPRESS -DZSTD_LZMADECOMPRESS
++@@ -130,7 +133,7 @@ endif
++ 
++ # lz4 detection
++ NO_LZ4_MSG := ==> no liblz4, building zstd without .lz4 support
++-HAVE_LZ4 := $(shell printf '\#include <lz4frame.h>\n\#include <lz4.h>\nint main(void) { return 0; }' > have_lz4.c && $(CC) $(FLAGS) -o have_lz4$(EXT) have_lz4.c -llz4 2> $(VOID) && rm have_lz4$(EXT) && echo 1 || echo 0; rm have_lz4.c)
+++HAVE_LZ4 := $(shell printf '$(NUM_SYMBOL)include <lz4frame.h>\n\#include <lz4.h>\nint main(void) { return 0; }' > have_lz4.c && $(CC) $(FLAGS) -o have_lz4$(EXT) have_lz4.c -llz4 2> $(VOID) && rm have_lz4$(EXT) && echo 1 || echo 0; rm have_lz4.c)
++ ifeq ($(HAVE_LZ4), 1)
++ LZ4_MSG := ==> building zstd with .lz4 compression support
++ LZ4CPP = -DZSTD_LZ4COMPRESS -DZSTD_LZ4DECOMPRESS
++-- 
++2.26.2
++
diff --git a/patches/openwrt/0011-build-compress-kernel-debuginfo-using-zstd.patch b/patches/openwrt/0011-build-compress-kernel-debuginfo-using-zstd.patch
new file mode 100644
index 000000000..66678df24
--- /dev/null
+++ b/patches/openwrt/0011-build-compress-kernel-debuginfo-using-zstd.patch
@@ -0,0 +1,43 @@
+From: Matthias Schiffer <mschiffer@universe-factory.net>
+Date: Wed, 13 May 2020 20:33:46 +0200
+Subject: build: compress kernel debuginfo using zstd
+
+zstd with its default settings (compression level -3) compresses better
+than bzip2 -9 (which is the default setting), and is an order of magnitude
+faster.
+
+I made the following measurements for the most common compression tools
+(all standard Debian Buster versions, default flags unless noted
+otherwise), using the debug information of a large x86-64 kernel with
+ALL_KMODS:
+
+* kernel-debug.tar: 376M
+* kernel-debug.tar.gz: 101M, compressed in ~12s
+* kernel-debug.tar.bz2: 91M, compressed in ~15s
+* kernel-debug.tar.xz: 57M, compressed in ~101s
+* kernel-debug.tar.zst: 86M, compressed in ~1s
+
+With zstd, there is still some room for improvement by increasing the
+compression, but the slight increase in compression ratio
+(22.83% -> 19.46%) does not justify the significant increase in
+compression time (about 5 times on my machine) in my opinion.
+
+Note that multithreaded compression (-T argument) does not affect
+reproducibility with zstd.
+
+Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
+(cherry picked from commit 4bd7990488b0ca7b5cae16f0a9147a4146759053)
+
+diff --git a/include/kernel-build.mk b/include/kernel-build.mk
+index 3fdf7efc52857a5184348cc1261848f75751b8a9..af7c3a8f0bb15c7e0d7072876705ff0bf4f9c8d1 100644
+--- a/include/kernel-build.mk
++++ b/include/kernel-build.mk
+@@ -70,7 +70,7 @@ ifdef CONFIG_COLLECT_KERNEL_DEBUG
+ 	$(FIND) $(KERNEL_BUILD_DIR)/debug -type f | $(XARGS) $(KERNEL_CROSS)strip --only-keep-debug
+ 	$(TAR) c -C $(KERNEL_BUILD_DIR) debug \
+ 		$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
+-		| bzip2 -c -9 > $(BIN_DIR)/kernel-debug.tar.bz2
++		| zstd -T0 -f -o $(BIN_DIR)/kernel-debug.tar.zst
+   endef
+ endif
+ 
-- 
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