Re: [Libvir] New vs old-style hypercalls

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.