> On Aug 24, 2020, at 2:02 PM, Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > > 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? It disables the EXPORT_SYMBOL() macros inside of lib/zstd/decompress.c. On x86 the kernel won’t boot with these defined. Other decompressors hide them if the STATIC macro is defined, but zstd uses this method, which was added somewhat recently. -Nick > -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
