Re: Odd stacksize problem

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

adam.hoka%gmail.com@localhost said:
> increasing the stack size to 8M makes it overlap with something else

This can be explained:
On i386, the user address space ends at 0xbfc00000. This is
at a 4M alignment boundary, but in the middle of a naturally
aligned 8M block. Stack allocation in libpthread is rather
simplistic: it can only deal with naturally aligned ranges, all
of the same size which is power-of-two.
(The deeper reason is that the stack pointer value is the only
means to identify a thread.)
So the 8M block which matches the initial stack pointer is
only usable in the lower half, the upper half is already
kernel space.
(This also means that pthread_attr_setstacksize() etc are of
limited value.)

best regards
Matthias




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