Re: tip: bzip2/lzma now in tip:x86/setup-lzma

Alain Knaff
2009-02-19T20:11:47Z

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Alain Knaff wrote:
> hmmm, but on a second glance, there seems to be indeed an issue. When
> compiling it a _second time_, compilation will "succeed" but produce a
> bad kernel because the first attempt left an empty
> usr/initramfs_data.cpio.bz2 .
>
> I'll look into it this evening, probably a case of "bad" failure
> recovery in the Makefile.
>

Took me slightly longer than promised, attached is the patch.

It changes/fixes three things:
1. Fix a bug in decompress.c : only scanned until the first
non-configured compressor (with disastrous result if that was gzip)
2. Fix a bug in gen_initramfs_list.sh : in case of failure, it left
indeed an empty output file behind, messing up the next make.
3. Make builtin initramfs compression configurable

Regards,

Alain

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This changes three things:
1. Fix a bug in decompress.c : only scanned until the first
non-configured compressor (with disastrous result if that was gzip)
2. Fix a bug in gen_initramfs_list.sh : in case of failure, it left an
empty output file behind, messing up the next make.
3. Make builtin initramfs compression configurable

Signed-off-by: Alain Knaff <alain@knaff.lu>

---

diff -purN base/lib/decompress.c i386/lib/decompress.c
--- base/lib/decompress.c 2009-02-18 07:59:07.000000000 +0100
+++ i386/lib/decompress.c 2009-02-19 20:56:07.000000000 +0100
@@ -43,7 +43,7 @@ decompress_fn decompress_method(const un
if (len < 2)
return NULL; /* Need at least this much... */

- for (cf = compressed_formats; cf->decompressor; cf++) {
+ for (cf = compressed_formats; cf->name; cf++) {
if (!memcmp(inbuf, cf->magic, 2))
break;

diff -purN base/scripts/gen_initramfs_list.sh i386/scripts/gen_initramfs_list.sh
--- base/scripts/gen_initramfs_list.sh 2009-02-18 07:59:07.000000000 +0100
+++ i386/scripts/gen_initramfs_list.sh 2009-02-19 07:52:57.000000000 +0100
@@ -292,7 +292,7 @@ if [ ! -z ${output_file} ]; then
if [ "${is_cpio_compressed}" = "compressed" ]; then
cat ${cpio_tfile} > ${output_file}
else
- cat ${cpio_tfile} | ${compr} - > ${output_file}
+ (cat ${cpio_tfile} | ${compr} - > ${output_file}) || (rm ${output_file} ; false)
fi
[ -z ${cpio_file} ] && rm ${cpio_tfile}
fi
diff -purN base/usr/Kconfig i386/usr/Kconfig
--- base/usr/Kconfig 2009-02-18 07:59:07.000000000 +0100
+++ i386/usr/Kconfig 2009-02-19 20:02:41.000000000 +0100
@@ -71,3 +71,65 @@ config RD_LZMA
help
Support loading of a lzma encoded initial ramdisk or cpio buffer
If unsure, say N.
+
+choice
+ prompt "Built-in initramfs compression mode"
+ help
+ This setting is only meaningful if the INITRAMFS_SOURCE is
+ set. It decides by which algorithm the INITRAMFS_SOURCE will
+ be compressed.
+ Several compression algorithms are available, which differ
+ in efficiency, compression and decompression speed.
+ Compression speed is only relevant when building a kernel.
+ Decompression speed is relevant at each boot.
+
+ If you have any problems with bzip2 or lzma compressed
+ initramfs, mail me (Alain Knaff) <alain@knaff.lu>.
+
+ High compression options are mostly useful for users who
+ are low on disk space (embedded systems), but for whom ram
+ size matters less.
+
+ If in doubt, select 'gzip'
+
+config INITRAMFS_COMPRESSION_NONE
+ bool "None"
+ help
+ Do not compress the built-in initramfs at all. This may
+ sound wasteful in space, but, you should be aware that the
+ built-in initramfs will be compressed at a later stage
+ anyways along with the rest of the kernel, on those
+ architectures that support this.
+ However, not compressing the initramfs may lead to slightly
+ higher memory consumption during a short time at boot, while
+ both the cpio image and the unpacked filesystem image will
+ be present in memory simultaneously
+
+config INITRAMFS_COMPRESSION_GZIP
+ bool "Gzip"
+ depends on RD_GZIP
+ help
+ The old and tried gzip compression. Its compression ratio is
+ the poorest among the 3 choices; however its speed (both
+ compression and decompression) is the fastest.
+
+config INITRAMFS_COMPRESSION_BZIP2
+ bool "Bzip2"
+ depends on RD_BZIP2
+ help
+ Its compression ratio and speed is intermediate.
+ Decompression speed is slowest among the three. The initramfs
+ size is about 10% smaller with bzip2, in comparison to gzip.
+ Bzip2 uses a large amount of memory. For modern kernels you
+ will need at least 8MB RAM or more for booting.
+
+config INITRAMFS_COMPRESSION_LZMA
+ bool "LZMA"
+ depends on RD_LZMA
+ help
+ The most recent compression algorithm.
+ Its ratio is best, decompression speed is between the other
+ two. Compression is slowest. The initramfs size is about 33%
+ smaller with LZMA in comparison to gzip.
+
+endchoice
diff -purN base/usr/Makefile i386/usr/Makefile
--- base/usr/Makefile 2009-02-18 07:59:07.000000000 +0100
+++ i386/usr/Makefile 2009-02-19 20:27:31.000000000 +0100
@@ -5,24 +5,18 @@
klibcdirs:;
PHONY += klibcdirs

-# Find out "preferred" ramdisk compressor. Order of preference is
-# 1. bzip2 efficient, and likely to be present
-# 2. gzip former default
-# 3. lzma
-# 4. none

-# None of the above
-suffix_y =
-
-# Lzma, but no gzip nor bzip2
-suffix_$(CONFIG_RD_LZMA) = .lzma
+# No compression
+suffix_$(CONFIG_INITRAMFS_COMPRESSION_NONE) =

# Gzip, but no bzip2
-suffix_$(CONFIG_RD_GZIP) = .gz
+suffix_$(CONFIG_INITRAMFS_COMPRESSION_GZIP) = .gz

# Bzip2
-suffix_$(CONFIG_RD_BZIP2) = .bz2
+suffix_$(CONFIG_INITRAMFS_COMPRESSION_BZIP2) = .bz2

+# Lzma
+suffix_$(CONFIG_INITRAMFS_COMPRESSION_LZMA) = .lzma

# Generate builtin.o based on initramfs_data.o
obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data$(suffix_y).o