Re: [RFC] ARM binutils feature churn causing kernel problems

Paulo Marques
2004-10-07T17:06:10Z

Russell King wrote:
> On Thu, Oct 07, 2004 at 01:35:32PM +0100, Paulo Marques wrote:
>
>>The patch by Russel King seems ok to me, although I prefer Rusty's idea
>>of not using any symbol that is not in the form "[A-Za-z0-9_]+". We just
>>need to check if there are any real world users of these "weird" symbols.
>
>
> This may filter out too much - we have symbols starting with a '.' on
> ARM, particularly used in some of the assembly code, which are useful
> to be decoded back to names, such as ".bug".
>
> However, including "." means that names like "__func__.0" also get
> included, which is probably a bad thing. So, maybe it needs to be
>
> [A-Za-z0-9_\.][A-Za-z0-9_]*

I just checked a "nm -n vmlinux" output on a x86 2.6.9-rc3-mm2 defconfig
kernel and it has stuff like:

...
c01aed13 t .text.lock.transaction
c01b1db3 t .text.lock.checkpoint
...
c03c7708 r single_rates.0
c03c7714 r double_rate_channels.1
...
c0482280 d get_s16_labels.0
c04822c0 d put_s16_labels.1
c0482300 d get_s16_labels.2
c0482340 d put_s16_labels.3
...
c053d780 b nulldevname.1
c053d800 b bootstrap.2
...

Most of these seem like useful information (although I personally don't
have any use for them).

The 'b' and 'r' types only get in if CONFIG_KALLSYMS_ALL is specified.

There were 572 "__func__.*" symbols all with type 'r'. If we take into
account that there were a total of 32881 symbols, these 572 are not that
many. Even more, with the new compression scheme they would probably
take only about 3 bytes per symbol to store the name and 4 bytes for the
address (8 on 64 bit architectures) that would require about 4kb of data
for users that choose the CONFIG_KALLSYMS_ALL option. Removing the
"__func__" symbols would represent less than a 2% decrease in size.

So maybe we could use "[A-Za-z0-9_\.]+" ?

--
Paulo Marques - www.grupopie.com

To err is human, but to really foul things up requires a computer.
Farmers' Almanac, 1978