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Old 05-20-2006, 04:40 AM   #1
xcore_on
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what's difference between bzImage and zImage?


- What's difference between bzImage and zImage? only compression mode?
- bzImage use bzip2 and zImage?


Thanks in advance!

Last edited by xcore_on; 05-20-2006 at 04:50 AM.
 
Old 05-20-2006, 09:36 AM   #2
Brian1
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bzImage just means Big zImage. zImage can only be a maximum size 512k. Unless the kernel will be that size or smaller after compiling then you need to make it as bzImage. Earlier kernels where quite able to fit in the 512k range but over time many new features have been added and the zImage limits were reach and something new had to be done.

Brian1

Last edited by Brian1; 05-20-2006 at 09:37 AM.
 
Old 05-20-2006, 11:49 AM   #3
Komakino
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Quote:
Originally Posted by Brian1
bzImage just means Big zImage. zImage can only be a maximum size 512k. Unless the kernel will be that size or smaller after compiling then you need to make it as bzImage. Earlier kernels where quite able to fit in the 512k range but over time many new features have been added and the zImage limits were reach and something new had to be done.

Brian1
Hey, that's really interesting! I'd always assumed bzimage was because it was bz2 compressed (which I guess it isn't, thinking about it...)
 
Old 05-20-2006, 12:21 PM   #4
xcore_on
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Brian1, so the only difference between bzImage and zImage is only compression mode?

bzImage use bzip2 and zImage use compress is is right?
 
Old 05-20-2006, 12:25 PM   #5
meng
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No, that's incorrect, but a popular misconception.
They both use zlib. Brian1 explained this nicely.
 
Old 05-20-2006, 01:53 PM   #6
xcore_on
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Hungry Minds - LPIC1 Certification Bible - 2001 - page 498:

make zImage - Creates a gzip’d kernel image that must be installed manually.
make bzImage - Creates a bzip2’d kernel image that must be installed manually.


so this is "a popular misconception"!?!?!

Last edited by xcore_on; 05-20-2006 at 01:54 PM.
 
Old 05-20-2006, 03:51 PM   #7
meng
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I believe that your reference is wrong. But ultimately, it's your decision which reference you trust more. Why don't you google around a bit more? I'd be fascinated to know what you decide.

Last edited by meng; 05-20-2006 at 03:52 PM.
 
Old 05-20-2006, 04:32 PM   #8
gilead
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The following is from the file Documentation/kbuild/commands.txt for the 2.2.26 kernel (starts at line 44):
Code:
Note: the difference between 'zImage' files and 'bzImage' files is that
'bzImage' uses a different layout and a different loading algorithm,
and thus has a larger capacity.  Both files use gzip compression.
The 'bz' in 'bzImage' stands for 'big zImage', not for 'bzip'!
 
Old 05-20-2006, 08:35 PM   #9
xcore_on
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So, others books wrongs:

O'Reilly - Lpi Linux Certification In A Nutshell - page 317:
The bzImage file is our ultimate goal, a bootable kernel image file,
compressed using the bzip2 utility.* It is created in this step along with some
additional support files needed for boot time.

Que - ExamCram2 LPIC - page 348:
zImage—Makes a compressed kernel using the gzip compression option.
bzImage—Makes a compressed kernel using the bzip2 compression option.


more others opnions:

Wave - Linux System Administration - page 318:
What is the difference between a zImage and a bzImage?
zImage must be used on non-i386 architectures and is also limited to a 1-MB
uncompressed file size. bzImage is not limited in its file size.


http://www.digitalhermit.com/linux/K...ld-HOWTO.html:
The difference between 'zImage' files and 'bzImage' files is that 'bzImage' uses a different layout and a different loading algorithm, and thus has a larger capacity. Both files use gzip compression. The 'bz' in 'bzImage' stands for 'big zImage', not for 'bzip'!


Sams - Red Hat Linux Fedora 3 Unleashed:
-zImage This directive compiles the kernel, creating an uncompressed file called zImage.
-bzImage This directive creates a compressed kernel image necessary for some systems that require the kernel image to be under a certain size for the BIOS to be able to parse them;


Hungry Minds - Debian GNU-Linux Bible:
Because the kernel image was too big in Step 2, you now need to use a different
compression method. Run make bzImage to create the image using the
alternative compression method.



aff, this is very complex!!!

so I am think in create my proper theory hahaha!
 
  


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