[PATCH] optional use "gzip --rsyncable" for bzImage

[PATCH] optional use "gzip --rsyncable" for bzImage

[Ph. Marek]

Hello everybody!


As (at least in debian) gzip has the "--rsyncable" parameter included, 
I'd like to suggest this patch to (configurable) use this for bzImage creation.

The default is "N" to stay compatible with current behaviour.


I didn't find an entry in MAINTAINERS; and according to git a lot of people 
touch arch/i386/Kconfig, so I just send to the l-k.

Andrew, how about an -mm inclusion? Or is the patch too small to warrant that?



Regards,

Phil



From: philipp.marek@bmlv.gv.at

diff -urN linux-2.6.12.orig/arch/i386/boot/compressed/Makefile linux-2.6.12/arch/i386/boot/compressed
/Makefile
--- linux-2.6.12.orig/arch/i386/boot/compressed/Makefile        2005-06-17 21:48:29.000000000 +0200
+++ linux-2.6.12/arch/i386/boot/compressed/Makefile     2005-11-16 13:44:34.000000000 +0100
@@ -4,6 +4,12 @@
 # create a compressed vmlinux image from the original vmlinux
 #

+ifdef CONFIG_RSYNCABLE
+GZIP_OPT       := --rsyncable
+else
+GZIP_OPT       :=
+endif
+
 targets                := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o
 EXTRA_AFLAGS   := -traditional

@@ -17,7 +23,7 @@
        $(call if_changed,objcopy)

 $(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
-       $(call if_changed,gzip)
+       $(call if_changed,gzip $(CONFIG_RSYNCABLE))

 LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T

diff -urN linux-2.6.12.orig/arch/i386/Kconfig linux-2.6.12/arch/i386/Kconfig
--- linux-2.6.12.orig/arch/i386/Kconfig 2005-06-17 21:48:29.000000000 +0200
+++ linux-2.6.12/arch/i386/Kconfig      2005-11-16 13:27:12.000000000 +0100
@@ -922,6 +922,17 @@
        generate incorrect output with certain kernel constructs when
        -mregparm=3 is used.

+config RSYNCABLE
+       bool "Make bzImage better rsyncable (EXPERIMENTAL)"
+       depends on EXPERIMENTAL
+       default n
+       help
+       Compresses the kernel with "gzip --rsyncable". This makes the kernel
+       slightly larger (1-2%), but allows rsync to synchronize.
+
+
 config SECCOMP
        bool "Enable seccomp to safely compute untrusted bytecode"
        depends on PROC_FS

Re: [PATCH] optional use "gzip --rsyncable" for bzImage

[Andrew Morton]

"Ph. Marek" <philipp.marek@bmlv.gv.at> wrote:
>
>  As (at least in debian) gzip has the "--rsyncable" parameter included, 
>  I'd like to suggest this patch to (configurable) use this for bzImage creation.

I'd doubt if this works with a compressed a.out.  Most changes one would
make to a kernel at the source level will cause changes all over the
generated binary, so rsync will send the whole compressed file anyway.

For example, a few-byte change in size of a function will cause a huge
number of `call xxxxxxxx' opcodes to turn into `call xxxxxxxx+N'.

So I'll need some convincing.  But even if convinced, this seems like an
exceedingly obscure thing that not many people would be interested in.

echo `/usr/bin/gzip --rsyncable $*' > ~/bin/gzip ;)

Re: [PATCH] optional use "gzip --rsyncable" for bzImage

[Alistair John Strachan]

On Thursday 17 November 2005 01:54, Andrew Morton wrote:
> "Ph. Marek" <philipp.marek@bmlv.gv.at> wrote:
> >  As (at least in debian) gzip has the "--rsyncable" parameter included,
> >  I'd like to suggest this patch to (configurable) use this for bzImage
> > creation.
>
> I'd doubt if this works with a compressed a.out.  Most changes one would
> make to a kernel at the source level will cause changes all over the
> generated binary, so rsync will send the whole compressed file anyway.
>
> For example, a few-byte change in size of a function will cause a huge
> number of `call xxxxxxxx' opcodes to turn into `call xxxxxxxx+N'.
>
> So I'll need some convincing.  But even if convinced, this seems like an
> exceedingly obscure thing that not many people would be interested in.

Sounds like a patch for the debian kernel team, since GNU's latest alpha gzip 
version doesn't support --rsyncable.

[alistair] 00:34 [~] gzip --rsyncable
gzip: unrecognized option `--rsyncable'
gzip 1.3.5

-- 
Cheers,
Alistair.

'No sense being pessimistic, it probably wouldn't work anyway.'
Third year Computer Science undergraduate.
1F2 55 South Clerk Street, Edinburgh, UK.