Question from Russells Spinlocks

[Imanpreet Singh Arora]

Hello there,

   I was reading Russell's guide on spinlocks, and I have some 
questions regarding it.


   Question-->    Russell says that in case of non-SMP machines 
spinlocks don't exist _at_ALL_. Well they should do something don't they 
like disable interrupts and premptations. I checked linux/spinlock well 
they DO NOT do anything atleast not when DEBUG_SPINLOCKS == 0. My 
understanding is that since they aren't used anywhere outside kernel and 
drivers(?), they can't be prempted. At least that is what I have read.


What does the comment about gcc while defining atomic_t signify?
            --> What about the comment about the limit of 24 bits on 
atomic_t?    
            a)    Atomic operations on integers are guranteed only if 
there value can be stored in 24 bits.
            b)    Atomic operations are guranteed only if the pointer 
has 8 MSbits set zero.


--
Imanpreet Singh Arora

Even if you are on the right track you are going to get runover if you just sit there.
	-- Will Rogers


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