On Wed, May 28, 2014 at 11:52:12PM +0200, Andreas Herrmann wrote:
> +/*
> + * Hypercalls for KVM.
> + *
> + * Hypercall number is passed in v0.
> + * Return value will be placed in v0.
> + * Up to 3 arguments are passed in a0, a1, and a2.
> + */
> +static inline unsigned long kvm_hypercall0(unsigned long num)
> +{
> + register unsigned long n asm("v0");
> + register unsigned long r asm("v0");
Btw, is it safe to put two variables in the same register?
The syscall wrappers that used to be in <asm/unistd.h> were occasionally
hitting problems which eventually forced me to stop forcing variables
into particular registers instead using a MOVE instruction to shove
each variable into the right place.
Of course they were being used from non-PIC and PIC code, kernel and userland
so GCC had a much better chance to do evil than in the hypercall wrapper
case - but it made me paranoid ...
Ralf
