Re: kernel size

From: vda (
Date: Wed Oct 10 2001 - 09:47:10 EST

Hello Richard,
Wednesday, October 10, 2001, 3:00:32 PM, you wrote:

RBJ> Yes... but. The final test was using bzImage which became about 1k
RBJ> shorter after making the changes to
RBJ> -rw-r--r-- 1 root root 575432 Oct 9 13:49 bzImage
RBJ> -rw-r--r-- 1 root root 581384 Oct 1 13:27 bzImage.OLD
RBJ> The size change of the raw image is even more evident:
RBJ> -rwxr-xr-x 1 root root 1548916 Oct 9 13:49 vmlinux
RBJ> -rwxr-xr-x 1 root root 1590692 Oct 1 13:26 vmlinux.OLD
RBJ> Also I was not complaining about anything. One respondent noted
RBJ> that compiling the kernel with a new 'C' compiler resulted in
RBJ> a large increase in kernel size. Some of us then attempted to
RBJ> find out simple ways to get the kernel size back down. I showed
RBJ> that some 'C' compiler versions have enormous ID strings that
RBJ> are wasting space. I also mentioned that some versions align
RBJ> everything on 16-byte boundaries and there doesn't seem to
RBJ> be any way to turn off this 'feature'.

Ok. Learning from makefiles: bzImage's copressed part is made
by gzipping toplevel 'vmlinux' processed via objcopy.

If anybody feel so inclined, I suggest doing
#objdump -O binary -R .note -R .comment -S vmlinux vmlinux.stripped
(that's what make bzImage does, feeding result to gzip)
and inspecting 'vmlinux.stripped' for large zeroed areas
and big/strange regular patterns. That might be oversized tables.

I'd like to be enlightened how I can translate offsets in
'vmlinux.stripped' to corresponding kernel func/var...

Best regards, vda

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