Re: [Qemu-devel] [RFC v9 06/27] virtio-blk: Take PCI memory range into account

[Avi Kivity <avi@redhat.com>]

On 07/19/2012 12:16 PM, Stefan Hajnoczi wrote:
> On Thu, Jul 19, 2012 at 10:14 AM, Stefan Hajnoczi <stefanha@gmail.com> wrote:
>> On Wed, Jul 18, 2012 at 7:29 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
>>> On Wed, Jul 18, 2012 at 04:07:33PM +0100, Stefan Hajnoczi wrote:
>>>> Support >4 GB physical memory accesses.
>>>>
>>>> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
>>>
>>> Need some sane APIs, this is just too scary.
>>
>> Yes, this prototype has (at least) two layering violations:
>> 1. Bypassing QEMU's memory subsystem because it isn't thread-safe.
> 
> Maybe we can use MemoryListener to fix this, although we need to take
> care of thread-safety.

Better to fix up the memory core.  It should be relatively easy to
rcu-ify it, as it already works by building a new memory map instead of
updating it in place.  Currently it has one root pointer, all that is
needed is to build it into a temporary pointer, then use
rcu_assign_pointer() to atomically switch the memory map.


-- 
error compiling committee.c: too many arguments to function