Re: [Qemu-devel] [PATCH] spapr_pci: Advertise MSI quota

[Alexander Graf <agraf@suse.de>]

On 11.06.14 10:18, Alexey Kardashevskiy wrote:
> On 06/11/2014 06:06 PM, Alexander Graf wrote:
>> On 11.06.14 10:05, Alexey Kardashevskiy wrote:
>>> From: Badari Pulavarty <pbadari@us.ibm.com>
>>>
>>> Hotplug of multiple disks fails due to MSI vector quota check.
>>> Number of MSI vectors default to 8 allowing only 4 devices.
>>> This happens on RHEL6.5 guest. RHEL7 and SLES11 guests fallback
>>> to INTX.
>>>
>>> One way to workaround the issue is to increase total MSIs,
>>> so that MSI quota check allows us to hotplug multiple disks.
>>>
>>> Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
>>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>> ---
>>>    hw/ppc/spapr_pci.c | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
>>> index ddfd8bb..ebd92fd 100644
>>> --- a/hw/ppc/spapr_pci.c
>>> +++ b/hw/ppc/spapr_pci.c
>>> @@ -831,6 +831,7 @@ int spapr_populate_pci_dt(sPAPRPHBState *phb,
>>>        int bus_off, i, j;
>>>        char nodename[256];
>>>        uint32_t bus_range[] = { cpu_to_be32(0), cpu_to_be32(0xff) };
>>> +    uint16_t nmsi = 64;
>> Why 64?
> Why not? :)
> We need some number here instead of default 8, that's pretty much it. 256?

How is 64 any better than 8? How many MSIs can we support? Can't we just 
put that number in? If it's more than 64k, just put in 64k?


Alex