[Xen-devel] 32/64-bit hypercall interface

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

I was looking at the definition of privcmd_hypercall:
typedef struct privcmd_hypercall
{
    unsigned long op;
    unsigned long arg[5];
} privcmd_hypercall_t;

For ppc64, we are using 32-bit management tools, so this is a problem: they 
will create structs where long is 32 bits, and the (64-bit) kernel and 
hypervisor will expect structs where long is 64 bits.

The standard (and awkward) way of dealing with the privcmd ioctl is to create 
an in-kernel privcmd_hypercall_t, copy the 32-bit values into it field by 
field, and then pass *that* struct on to privcmd_ioctl(). Of course, that's 
only for legacy interfaces; for all new interfaces, we can just design them 
properly so that their size and alignment doesn't change.

There are also longs in some of the dom0_op sub-structures. For example:
typedef struct {
    /* IN variables. */
    domid_t       domain;
    unsigned long max_memkb;
} dom0_setdomainmaxmem_t;

I suggest that all longs in these structures be converted to u32.

-- 
Hollis Blanchard
IBM Linux Technology Center

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