[PATCH] ppc64: Implement a vDSO and use it for signal trampoline

Sam Ravnborg sam at ravnborg.org
Tue Feb 1 16:41:49 EST 2005

On Tue, Feb 01, 2005 at 11:38:02AM +1100, Benjamin Herrenschmidt wrote:
> > Also notice that ':=' uses all over. No need to use late evaluation when
> > no dynamic references are used ($ $@ etc.).
> Hrm... Rusty tells me that you got it backward ;) Anyway, I'll stick
> to := for now, it's not really an issue.

Right hand side is evaluated when encountered.
Often what you want. So for example
CC := cc
here CC is assigned the value cc when seen.

Right hand side is evaluated only when left hand side is used.
Also very usefull. Example just mocked up:
cmd_vdso32_cc = $(CC) -T $^ -o $@

Doing late evaluation will cause correct replacement of $^ and $@ when
used. When cmd_vdso_32 is defined make does not know the desired values
for $^ and $@ - this is only known when cmd_vdso_32 is actually used.

Hope this clarifies it.


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