On Tue, Jun 12, 2007 at 03:34:04PM +0100, Richard W.M. Jones wrote:
> In xen_internal.c we've got code which claims to sniff out whether we
> are using new-style hypercall ioctls or old-style hypercall ioctls.
>
> hc.op = __HYPERVISOR_xen_version;
> hc.arg[0] = (unsigned long) XENVER_version;
> hc.arg[1] = 0;
>
> cmd = IOCTL_PRIVCMD_HYPERCALL;
> ret = ioctl(fd, cmd, (unsigned long) &hc);
>
> if ((ret != -1) && (ret != 0)) {
> #ifdef DEBUG
> fprintf(stderr, "Using new hypervisor call: %X\n", ret);
> #endif
> hv_version = ret;
> xen_ioctl_hypercall_cmd = cmd;
> goto detect_v2;
> }
>
> /*
> * check if the old hypercall are actually working
> */
> v0_hc.op = __HYPERVISOR_xen_version;
> v0_hc.arg[0] = (unsigned long) XENVER_version;
> v0_hc.arg[1] = 0;
> cmd = _IOC(_IOC_NONE, 'P', 0, sizeof(v0_hypercall_t));
> ret = ioctl(fd, cmd, (unsigned long) &v0_hc);
>
> But on 64 bit platforms (not 32 bit) cmd will be identical, so we'll
> just be trying the same ioctl twice.
>
> From <xen/linux/privcmd.h>:
>
> typedef struct privcmd_hypercall
> {
> __u64 op;
> __u64 arg[5];
> } privcmd_hypercall_t;
>
> #define IOCTL_PRIVCMD_HYPERCALL \
> _IOC(_IOC_NONE, 'P', 0, sizeof(privcmd_hypercall_t))
>
> From src/xen_internal.c:
>
> typedef struct v0_hypercall_struct {
> unsigned long op;
> unsigned long arg[5];
> } v0_hypercall_t;
>
> cmd = _IOC(_IOC_NONE, 'P', 0, sizeof(v0_hypercall_t));
>
> On 64 bit platforms, both structures will be the same size.
yes but I prefer doing an extra hypercall once at the library init than
trying to dig out whether on that particuliar box the structure will be
the same or not.
Daniel
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Daniel Veillard | virtualization library http://libvirt.org/
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