Re: [Xen-devel] [PATCH 3/3] x86/xen: use the maximum MFN to calculate the required DMA mask

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.11.14 at 11:38, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 12/11/14 15:55, Jan Beulich wrote:
>>>>> On 12.11.14 at 16:25, <david.vrabel@xxxxxxxxxx> wrote:
>>> +u64
>>> +xen_swiotlb_get_required_mask(struct device *dev)
>>> +{
>>> +   u64 max_mfn;
>>> +
>>> +   max_mfn = HYPERVISOR_memory_op(XENMEM_maximum_ram_page, NULL);
>>> +
>>> +   return DMA_BIT_MASK(fls64(max_mfn << PAGE_SHIFT) + 1);
>>> +}
>> The value the hypercall returns is exclusive and an unsigned long.
> 
> All hypercalls return long, despite lack of clarity, or in some cases,
> documentation to the contrary.

The emphasis wasn't on "unsigned" but on "long". But see also my
later reply to that same mail.

Jan


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