Re: pyxc_linux_build() in tools/python/xen/lowlevel/xc/xc.c still needed?

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

On 06/10/15 10:32, Andrew Cooper wrote:
> On 06/10/15 10:11, Roger Pau Monné wrote:
>> El 06/10/15 a les 10.56, Ian Campbell ha escrit:
>>> On Tue, 2015-10-06 at 08:33 +0200, Juergen Gross wrote:
>>>> Do we have any requirements to be compatible to old releases regarding
>>>> the functions in tools/python/xen/lowlevel/xc/xc.c ?
>>> IMHO, no.
>>>
>>> There are also too many compatibility shims in front of the domain builder,
>>> i.e. all the stuff in tools/libxc/xc_dom_compat_linux.c which IMHO could be
>>> nuked too.
>>>
>>>> Especially pyxc_linux_build() isn't used anywhere in the tree. And this
>>>> is the only function setting xc_dom_image.superpages, thus removing it
>>>> would give us the chance to remove some code of the domain builder.
>>> Right. 
>>>
>>> Removing the superpages option from the non-Python might cause concern for
>>> some. Adding Konrad since IIRC PV superpages is a thing Oracle implemented
>>> and might still care about.
>>>
>>> Also adding Roger since he is reworking the HVM builder to use the PV one,
>>> which for all I know might involve using the superpage option (but probably
>>> not the PV code to set it up).
>> The superpages field is only used to populate memory of PV domains,
>> AFAICT HVM domains will already try to use superpages by default in
>> order to fill the p2m. I don't have any problem with it being removed.
> There is a key difference between PV guests and HVM guests when it comes
> to superpages.
>
> A PV guest needs to be explicitly capable of handling superpages, and it
> rules out things like migrate, etc.
>
> HVM superpages are just EPT/NPT superpages, without a direct effect on
> guest.
>
> I don't object to removing this field, but mistakenly equate PV and HVM
> guests in this regard.

Apologies.  "but don't mistakenly"

~Andrew