Jamie Prescott writes:
> > From: Adam Nemet <[email protected]>
> > Jamie Prescott writes:
> > > static inline int set_prop(char const *path, char const *name,
> > > void const *data, int size)
> > > {
> > > int error;
> > >
> > > asm volatile ("int\t11\n\t"
> > > : "=a0" (error): "a0" (path), "a1" (name), "a2"
> > > (data),
> > > "a3" (size));
> > >
> > > return error;
> > > }
> > >
> > > extern int calc(int);
> > >
> > > int proc(int i)
> > > {
> > > int j = calc(i);
> > >
> > > return set_prop(0, 0, &j, sizeof(int));
> > > }
> > ...
> > >
> > > Why is the memory clobber required, and why GCC does not understand to
> > > sync the value to memory when passing the address to a function?
> >
> > Because you never inform GCC that you will use the value at
> > address *NAME. Try to use "m"(*name) rather than "a1"(name) in the asm.
>
> That's 'data', not 'name'. But OK, got it. unfortunately, I cannot use "m"
> since
> that value need to go into a specific register.
> Any other solution?
You can also have it *in addition* as an argument to the asm that's never
used:
asm volatile ("int\t11\n\t"
: "=a0" (error): "a0" (path), "a1" (name), "a2" (data),
"a3" (size), "m"(*data));
after changing data's type into something that can be dereferenced.
Adam
