On Mon, 16 Jul 2012, Filipe Rinaldi wrote:
On 16 July 2012 12:22, Aft nix <aftnix@gmail.com> wrote:
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
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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 -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================