Re: [Qemu-devel] [PATCH 10/17] s390x: keep hint on virtio managing size

[Alexander Graf]

On 18.04.2011, at 21:06, Aurelien Jarno wrote:

> On Fri, Apr 15, 2011 at 05:32:51PM +0200, Alexander Graf wrote:
>> The s390x virtio bus keeps management information on virtio after the top
>> of the guest's RAM. We need to be able to tell the guest the size of its
>> RAM (without virtio stuff), but also be able to trap when the guest accesses
>> RAM outside of its scope (including virtio stuff).
>> 
>> So we need a variable telling us the size of the virtio stuff, so we can
>> calculate the highest available RAM address from that.
>> 
>> While at it, also increase the maximum number of virtio pages, so we play
>> along well with more recent kernels that spawn a ridiculous number of virtio
>> console adapters.
>> 
>> Signed-off-by: Alexander Graf <address@hidden>
>> ---
>> hw/s390-virtio-bus.c |    3 +++
>> hw/s390-virtio-bus.h |    2 +-
>> target-s390x/cpu.h   |    3 +++
>> 3 files changed, 7 insertions(+), 1 deletions(-)
>> 
>> diff --git a/hw/s390-virtio-bus.c b/hw/s390-virtio-bus.c
>> index bb49e39..a90963b 100644
>> --- a/hw/s390-virtio-bus.c
>> +++ b/hw/s390-virtio-bus.c
>> @@ -60,6 +60,9 @@ static const VirtIOBindings virtio_s390_bindings;
>> 
>> static ram_addr_t s390_virtio_device_num_vq(VirtIOS390Device *dev);
>> 
>> +/* length of VirtIO device pages */
>> +target_phys_addr_t virtio_size = S390_DEVICE_PAGES * TARGET_PAGE_SIZE;
>> +
> 
> If this variable is never written, can it be declared const?

Does that improve anything for exported variables? Do they get put into a ro 
section then?


Alex