[Xen-devel] [PATCH 1/5] xen: Always calculate max_cpus value
andrew.cooper3 at citrix.com
Fri Jul 13 10:51:23 EDT 2012
On 13/07/12 14:19, Daniel Kiper wrote:
> On Thu, Jul 05, 2012 at 04:56:39PM +0100, Jan Beulich wrote:
>>>>> On 05.07.12 at 17:00, Daniel Kiper <daniel.kiper at oracle.com> wrote:
>>> max_cpus is not available since 20374 changeset (Miscellaneous data
>>> placement adjustments). It was moved to __initdata section. This section
>>> is freed after Xen initialization. Assume that max_cpus is always
>>> equal to XEN_HYPER_SIZE(cpumask_t) * 8.
>> Using nr_cpu_ids, when available, would seem a better fit. And
> Hmmm... I could not find such animal in Xen source code.
> However, maybe I missed something.
nr_cpu_ids was introduced into xen-unstable with c/s 23982:511d5e65a302
It is not present in 4.1 or earlier.
>> I donm't see why, on dumps from old hypervisors, you wouldn't
>> want to continue using max_cpus. Oh, wait, I see - you would
>> have to be able to tell whether it actually sits in .init.data, which
>> might not be strait forward.
> Yep, but I will try to improve that once again.
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com
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