Hi Nick,
Le lun. 24 août 2020 à 19:51, Nick Terrell <terrelln@xxxxxx> a écrit
:
On Aug 21, 2020, at 9:29 AM, Paul Cercueil <paul@xxxxxxxxxxxxxxx>
wrote:
Add support for self-extracting kernels with a ZSTD compression.
Tested on a kernel for the GCW-Zero, it allows to reduce the size
of the
kernel file from 4.1 MiB with gzip to 3.5 MiB with ZSTD, and boots
just
as fast.
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
arch/mips/Kconfig | 1 +
arch/mips/boot/compressed/Makefile | 1 +
arch/mips/boot/compressed/decompress.c | 4 ++++
arch/mips/boot/compressed/string.c | 16 ++++++++++++++++
4 files changed, 22 insertions(+)
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c95fa3a2484c..b9d7c4249dc9 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1890,6 +1890,7 @@ config SYS_SUPPORTS_ZBOOT
select HAVE_KERNEL_LZMA
select HAVE_KERNEL_LZO
select HAVE_KERNEL_XZ
+ select HAVE_KERNEL_ZSTD
config SYS_SUPPORTS_ZBOOT_UART16550
bool
diff --git a/arch/mips/boot/compressed/Makefile
b/arch/mips/boot/compressed/Makefile
index 6e56caef69f0..86ddc6fc16f4 100644
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -70,6 +70,7 @@ tool_$(CONFIG_KERNEL_LZ4) = lz4
tool_$(CONFIG_KERNEL_LZMA) = lzma
tool_$(CONFIG_KERNEL_LZO) = lzo
tool_$(CONFIG_KERNEL_XZ) = xzkern
+tool_$(CONFIG_KERNEL_ZSTD) = zstd
You can use zstd22 here. It will give you slightly better compression
without any additional memory usage. Also, you should add
-D__DISABLE_EXPORTS to the KBUILD_CFLAGS like x86 does [1].
Indeed, it's 0.01% smaller :)
What is __DISABLE_EXPORTS for?
-Paul
[1]
https://github.com/torvalds/linux/blob/master/arch/x86/boot/compressed/Makefile
-Nick
targets += vmlinux.bin.z
$(obj)/vmlinux.bin.z: $(obj)/vmlinux.bin FORCE
diff --git a/arch/mips/boot/compressed/decompress.c
b/arch/mips/boot/compressed/decompress.c
index 88f5d637b1c4..c61c641674e6 100644
--- a/arch/mips/boot/compressed/decompress.c
+++ b/arch/mips/boot/compressed/decompress.c
@@ -72,6 +72,10 @@ void error(char *x)
#include "../../../../lib/decompress_unxz.c"
#endif
+#ifdef CONFIG_KERNEL_ZSTD
+#include "../../../../lib/decompress_unzstd.c"
+#endif
+
const unsigned long __stack_chk_guard = 0x000a0dff;
void __stack_chk_fail(void)
diff --git a/arch/mips/boot/compressed/string.c
b/arch/mips/boot/compressed/string.c
index 43beecc3587c..ab95722ec0c9 100644
--- a/arch/mips/boot/compressed/string.c
+++ b/arch/mips/boot/compressed/string.c
@@ -27,3 +27,19 @@ void *memset(void *s, int c, size_t n)
ss[i] = c;
return s;
}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+ unsigned int i;
+ const char *s = src;
+ char *d = dest;
+
+ if ((uintptr_t)dest < (uintptr_t)src) {
+ for (i = 0; i < n; i++)
+ d[i] = s[i];
+ } else {
+ for (i = n; i > 0; i--)
+ d[i - 1] = s[i - 1];
+ }
+ return dest;
+}
--
2.28.0
