On Mon, 16 Jul 2012, Filipe Rinaldi wrote:

On 16 July 2012 12:22, Aft nix [off-list ref] wrote:

quoted

Hi,

The macro expansion of __read_mostly :

#define __read_mostly __attribute__((__section__(".data..read_mostly"))

This one is from cache.h

__init:
#define __init          __section(.init.text) __cold notrace

from init.h

__exit:

#define __exit          __section(.exit.text) __exitused __cold notrace

After searching through net i have not found any good explanation of
what is happening there.

Additonal question : I have heard about various "linker magic"
employed in kernel development. Any information
regarding this will be wonderful.

cheers

--
-aft

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Hi Aft,

These macros are used to assign a function or initialised variable
content to a specific section in memory. If you search for the linker
script of any architecture (*.lds.S files), you will see that these
variables and functions are placed in specific sections with names
like "__init_begin" and "__init_end". After the initialisation, Linux
can re-use for example the "init" memory.

  that's what's happening when you see that boot-time message:

"Freeing unused memory ..."

or whatever it is, something to that effect.

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
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