Re: hammer: MAP_32BIT

[Timothy Miller <miller@techsource.com>]

Ulrich Drepper wrote:
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> H. Peter Anvin wrote:
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> 
>>No, it requires 31-bit addresses, and there was a discussion about how
>>some things need 31-bit and some 32-bit addresses.
> 
> 
> That's completely irrelevant to my point.  Whether MAP_32BIT actually
> has a 31 bit limit or not doesn't matter, it's limited as well in the
> possible mmap blocks it can return.
> 
> The only thing I care about is to have a hint and not a fixed
> requirement for mmap().  All your proposals completely ignored this.
> 

If your program is capable of handling an address with more than 32 
bits, what point is there giving a hint?  Either your program can handle 
64-bit pointers or it cannot.  Any program flexible enough to handle 
either size dynamically would expend enough overhead checking that it 
would be worse than if it just made a hard choice.