Compressed kernel has its own drawback: decompressing takes time. Even
though the time is short enough to ignore for most cases but for cases when
time is critical decompressing time still matters.
The patch adds a 'CONFIG_KERNEL_RAW' configure choice so the built binary
can have no decompressing at all. The experiment shows:
kernel kernel size time in decompress_kernel
compressed (gzip) 3.3M 53ms
compressed (lz4) 4.5M 16ms
uncompressed 14M 2ms
Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
v2:
* add HAVE_KERNEL_RAW
* decode ELF kernel in place instead of getting another copy
* minor comment fix
---
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/Makefile | 3 +++
arch/x86/boot/compressed/misc.c | 18 +++++++++++++-----
init/Kconfig | 13 ++++++++++++-
scripts/Makefile.lib | 8 ++++++++
5 files changed, 37 insertions(+), 6 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a..207695c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -142,6 +142,7 @@ config X86
select HAVE_KERNEL_LZ4
select HAVE_KERNEL_LZMA
select HAVE_KERNEL_LZO
+ select HAVE_KERNEL_RAW
select HAVE_KERNEL_XZ
select HAVE_KPROBES
select HAVE_KPROBES_ON_FTRACE
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 44163e8..ed366e1 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -120,6 +120,8 @@ $(obj)/vmlinux.relocs: vmlinux FORCE
vmlinux.bin.all-y := $(obj)/vmlinux.bin
vmlinux.bin.all-$(CONFIG_X86_NEED_RELOCS) += $(obj)/vmlinux.relocs
+$(obj)/vmlinux.bin.raw: $(vmlinux.bin.all-y) FORCE
+ $(call if_changed,raw)
$(obj)/vmlinux.bin.gz: $(vmlinux.bin.all-y) FORCE
$(call if_changed,gzip)
$(obj)/vmlinux.bin.bz2: $(vmlinux.bin.all-y) FORCE
@@ -133,6 +135,7 @@ $(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) FORCE
$(obj)/vmlinux.bin.lz4: $(vmlinux.bin.all-y) FORCE
$(call if_changed,lz4)
+suffix-$(CONFIG_KERNEL_RAW) := raw
suffix-$(CONFIG_KERNEL_GZIP) := gz
suffix-$(CONFIG_KERNEL_BZIP2) := bz2
suffix-$(CONFIG_KERNEL_LZMA) := lzma
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b3c5a5f0..9791ca9 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -51,6 +51,10 @@
static int vidport;
static int lines, cols;
+#ifdef CONFIG_KERNEL_RAW
+#include <linux/decompress/mm.h>
+#endif
+
#ifdef CONFIG_KERNEL_GZIP
#include "../../../../lib/decompress_inflate.c"
#endif
@@ -265,7 +269,7 @@ static inline void handle_relocations(void *output, unsigned long output_len,
{ }
#endif
-static void parse_elf(void *output)
+static void parse_elf(void* buf, void *output)
{
#ifdef CONFIG_X86_64
Elf64_Ehdr ehdr;
@@ -277,7 +281,7 @@ static void parse_elf(void *output)
void *dest;
int i;
- memcpy(&ehdr, output, sizeof(ehdr));
+ memcpy(&ehdr, buf, sizeof(ehdr));
if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
@@ -292,7 +296,7 @@ static void parse_elf(void *output)
if (!phdrs)
error("Failed to allocate space for phdrs");
- memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
+ memcpy(phdrs, buf + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
for (i = 0; i < ehdr.e_phnum; i++) {
phdr = &phdrs[i];
@@ -305,7 +309,7 @@ static void parse_elf(void *output)
#else
dest = (void *)(phdr->p_paddr);
#endif
- memmove(dest, output + phdr->p_offset, phdr->p_filesz);
+ memmove(dest, buf + phdr->p_offset, phdr->p_filesz);
break;
default: /* Ignore other PT_* */ break;
}
@@ -401,10 +405,14 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
error("Destination virtual address changed when not relocatable");
#endif
+#ifdef CONFIG_KERNEL_RAW
+ parse_elf(input_data, output);
+#else
debug_putstr("\nDecompressing Linux... ");
__decompress(input_data, input_len, NULL, NULL, output, output_len,
NULL, error);
- parse_elf(output);
+ parse_elf(output, output);
+#endif
handle_relocations(output, output_len, virt_addr);
debug_putstr("done.\nBooting the kernel.\n");
return output;
diff --git a/init/Kconfig b/init/Kconfig
index a92f27d..b8926bb 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -109,6 +109,9 @@ config LOCALVERSION_AUTO
which is done within the script "scripts/setlocalversion".)
+config HAVE_KERNEL_RAW
+ bool
+
config HAVE_KERNEL_GZIP
bool
@@ -130,7 +133,7 @@ config HAVE_KERNEL_LZ4
choice
prompt "Kernel compression mode"
default KERNEL_GZIP
- depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
+ depends on HAVE_KERNEL_RAW || HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO || HAVE_KERNEL_LZ4
help
The linux kernel is a kind of self-extracting executable.
Several compression algorithms are available, which differ
@@ -149,6 +152,14 @@ choice
If in doubt, select 'gzip'
+config KERNEL_RAW
+ bool "RAW"
+ depends on HAVE_KERNEL_RAW
+ help
+ No compression. It creates much bigger kernel and uses much more
+ space (disk/memory) than other choices. It can be useful when
+ decompression speed is the most concern while space matters less.
+
config KERNEL_GZIP
bool "Gzip"
depends on HAVE_KERNEL_GZIP
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 0a07f90..8a8f9a9 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -357,6 +357,14 @@ cmd_lz4 = (cat $(filter-out FORCE,$^) | \
lz4c -l -c1 stdin stdout && $(call size_append, $(filter-out FORCE,$^))) > $@ || \
(rm -f $@ ; false)
+# RAW
+# ---------------------------------------------------------------------------
+quiet_cmd_raw = RAW $@
+cmd_raw = (cat $(filter-out FORCE,$^) && \
+ $(call size_append, $(filter-out FORCE,$^))) > $@ || \
+ (rm -f $@ ; false)
+
+
# U-Boot mkimage
# ---------------------------------------------------------------------------
--
1.8.3.1
--
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