Re: [PATCH] docs: fix superpage default value

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 20/07/17 13:57, Wei Liu wrote:
> On Thu, Jul 20, 2017 at 12:49:37PM +0100, Andrew Cooper wrote:
>> On 20/07/17 12:47, Wei Liu wrote:
>>> On Thu, Jul 20, 2017 at 12:45:38PM +0100, Roger Pau Monné wrote:
>>>> On Thu, Jul 20, 2017 at 12:35:56PM +0100, Wei Liu wrote:
>>>>> The code says it defaults to false.
>>>>>
>>>>> Signed-off-by: Wei Liu <wei.liu2@citrix.com>
>>>>> ---
>>>>> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
>>>>> Cc: George Dunlap <George.Dunlap@eu.citrix.com>
>>>>> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
>>>>> Cc: Jan Beulich <jbeulich@suse.com>
>>>>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>>>>> Cc: Stefano Stabellini <sstabellini@kernel.org>
>>>>> Cc: Tim Deegan <tim@xen.org>
>>>>> Cc: Wei Liu <wei.liu2@citrix.com>
>>>>> ---
>>>>>    docs/misc/xen-command-line.markdown | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
>>>>> index 3f90c3b7a8..f524294aa6 100644
>>>>> --- a/docs/misc/xen-command-line.markdown
>>>>> +++ b/docs/misc/xen-command-line.markdown
>>>>> @@ -136,7 +136,7 @@ mode during S3 resume.
>>>>>    ### allowsuperpage
>>>>>    > `= <boolean>`
>>>>> -> Default: `true`
>>>>> +> Default: `false`
>>>>>    Permit Xen to use superpages when performing memory management.
>>>> I'm not an expert on Xen MM code, but isn't this intended for PV
>>>> guests? The description above makes it look like this is for Xen
>>>> itself, but AFAICT from skimming over the code this seems to be a PV
>>>> feature, in which case the text above should be fixed to prevent
>>>> confusion.
>>> I believe it is PV only, but I'm not 100% sure.
>>>
>>> I would love to fix the text as well if possible.
>> I'm fairly sure this option applies exclusively to PV superpages. Double
>> check the logic through the code, but I think (since dropping 32bit
>> support), we have no configuration where Xen might not be able to use
>> superpages.
>>
> So we can just delete this option and make Xen always use superpage?
> That would be fine by me, too.

No - my point was that this option now exclusively controls PV 
superpages, IIRC.

~Andrew

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