On 05/19/2011 09:12 AM, Avi Kivity wrote:
The memory API separates the attributes of a memory region (its size,
how
reads or writes are handled, dirty logging, and coalescing) from
where it
is mapped and whether it is enabled. This allows a device to configure
a memory region once, then hand it off to its parent bus to map it
according
to the bus configuration.
Hierarchical registration also allows a device to compose a region
out of
a number of sub-regions with different properties; for example some
may be
RAM while others may be MMIO.
+ struct {
+ /* If nonzero, specify bounds on access sizes beyond which a
machine
+ * check is thrown.
+ */
+ unsigned min_access_size;
+ unsigned max_access_size;
+ /* If true, unaligned accesses are supported. Otherwise
unaligned
+ * accesses throw machine checks.
+ */
+ bool unaligned;
+ } valid;
Under what circumstances would this be used?
The behavior of devices that receive non-natural accesses varies wildly.
For PCI devices, invalid accesses almost always return ~0. I can't
think of a device where an MCE would occur.