[Libvir] New vs old-style hypercalls
Richard W.M. Jones
rjones at redhat.com
Tue Jun 12 14:34:04 UTC 2007
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.
Rich.
--
Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/
Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod
Street, Windsor, Berkshire, SL4 1TE, United Kingdom. Registered in
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