Re: [Qemu-devel] [kvmarm] [RFC v4 8/8] oslib-posix: Align to permit transparent hugepages on ARM Linux

[Peter Maydell]

On 20 November 2012 14:37, Alexander Graf <address@hidden> wrote:
> On 11/20/2012 02:55 PM, Christoffer Dall wrote:
>> On Tue, Nov 20, 2012 at 8:54 AM, Alexander Graf<address@hidden>  wrote:
>>> On 11/20/2012 02:31 PM, Peter Maydell wrote:
>>>> ARM Linux (like x86-64 Linux) can use transparent hugepages for
>>>> KVM if memory blocks are 2MiB aligned; set QEMU_VMALLOC_ALIGN
>>>> accordingly.

>>>> -#if defined(__linux__)&&   defined(__x86_64__)
>>>> +#if defined(__linux__)&&   (defined(__x86_64__) || defined(__arm__))
>>>
>>>
>>> Why not just drop the arch specific bit?

>> other archs have other alignment requirements, iirc.
>
> Ah, sorry, missed the rest of the lines around this one :).
> Yeah, should be ok then.

Yeah. Ideally the kernel would provide a mechanism so we can
ask at runtime what the preferred alignment is. (Or it could
just automatically provide it for suitably large allocations.)
In the absence of that this is just following along with the
current style.

-- PMM