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Re: [PATCH, newlib] Allow locking routine to be retargeted


Hello Thomas,

On 23/11/16 15:38, Thomas Preudhomme wrote:
Hi Sebastian,

I was thinking on how to solve this issue and found two possible solutions:

1) select size of lock at configure time

Instead of being an enable/disable option the configure option could take an integer value N that determine the size of lock, default being the size of a pointer. The lock would then be defined as an array of N integers.

Pro: LOCK_INIT works, simpler & smaller change
Cons: lock needs to be as big as the biggest lock among all the platforms you want to target wasting a bit of space.

2) Remove static initialization of locks

Remove all LOCK_INIT and add code as required to call lock_initialize at start up time.

Pro: you only pay the size for the lock you need (ie nothing except empty functions in the single threaded case)
Cons: much bigger work, start up cannot support multithread

3)

struct _lock;

typedef struct _lock *_LOCK_T;

#define __LOCK_INIT(class, lock) extern struct _lock _lock_ ## lock; class _LOCK_T lock = &_lock_ ## lock;

The OS must then provide struct _lock and storage for all statically initialized locks.

--
Sebastian Huber, embedded brains GmbH

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