From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: pyxc_linux_build() in
 tools/python/xen/lowlevel/xc/xc.c still needed?
Date: Tue, 6 Oct 2015 10:34:27 +0100
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To: =?windows-1252?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, Juergen Gross <jgross@suse.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>
List-Id: xen-devel@lists.xenproject.org

On 06/10/15 10:32, Andrew Cooper wrote:
> On 06/10/15 10:11, Roger Pau Monn=E9 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 buil=
der,
>>> i.e. all the stuff in tools/libxc/xc_dom_compat_linux.c which IMHO coul=
d 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 implemen=
ted
>>> and might still care about.
>>>
>>> Also adding Roger since he is reworking the HVM builder to use the PV o=
ne,
>>> which for all I know might involve using the superpage option (but prob=
ably
>>> 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