Jake Burkholder wrote:
> The system call stubs in libc are leaf functions; basically just a
> trap instruction followed by a return.  They do not touch the stack
> at all, or change the stack pointer.  One of the first few instructions
> on entry to the kernel is a save, which rotates the register window
> and logically saves the call-safe registers onto the user stack
> (the outs become the ins, and the kernel gets new ins and locals,
> with the old ones being saved to the user stack once a flush is
> performed or they get spilled out).
> Here is a reference:  http://www.sparc.com/standards/v9.ps.Z

Cool.  Thanks for the reference.  Though I think it's largely
equivalent to the system call helper for threads context and
stack switching in liblwp... 8-).

-- Terry

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