One question to p2m type

One question to p2m type

[Jiang, Yunhong]

Tim, one question to the p2m type.
As you reminded before, in PAE environment, p2m type can only hold 8 types in total, that means we should not have > p2m_grant_map_ro in p2m table. 

However, I didn't find any code to make sure this. For example, I didn't find any code to make sure mem_paging_domctl can't execut in PAE environment. Is it because p2m_change_type to >8 type will only impact guet itself, and we don't need to care for it?

Thanks
--jyh

Re: One question to p2m type

[Tim Deegan]

Hi, 

At 10:57 +0100 on 28 Jun (1277722666), Jiang, Yunhong wrote:
> As you reminded before, in PAE environment, p2m type can only hold 8
> types in total, that means we should not have > p2m_grant_map_ro in
> p2m table.
> 
> However, I didn't find any code to make sure this. For example, I
> didn't find any code to make sure mem_paging_domctl can't execut in
> PAE environment. Is it because p2m_change_type to >8 type will only
> impact guet itself, and we don't need to care for it?

No, that looks like an oversight.  All that memory-event code relies on
having enough p2m types available and probably shouldn't even be
compiled on PAE Xen.  It's certainly not expected to fail gracefully.
I'll knock up a patch.

Thanks, 

Tim.

-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

RE: One question to p2m type

[Jiang, Yunhong]

>-----Original Message-----
>From: Tim Deegan [mailto:Tim.Deegan@citrix.com]
>Sent: Monday, June 28, 2010 10:13 PM
>To: Jiang, Yunhong
>Cc: xen-devel
>Subject: Re: One question to p2m type
>
>Hi,
>
>At 10:57 +0100 on 28 Jun (1277722666), Jiang, Yunhong wrote:
>> As you reminded before, in PAE environment, p2m type can only hold 8
>> types in total, that means we should not have > p2m_grant_map_ro in
>> p2m table.
>>
>> However, I didn't find any code to make sure this. For example, I
>> didn't find any code to make sure mem_paging_domctl can't execut in
>> PAE environment. Is it because p2m_change_type to >8 type will only
>> impact guet itself, and we don't need to care for it?
>
>No, that looks like an oversight.  All that memory-event code relies on
>having enough p2m types available and probably shouldn't even be
>compiled on PAE Xen.  It's certainly not expected to fail gracefully.
>I'll knock up a patch.

Really thanks for clarification.

--jyh

>
>Thanks,
>
>Tim.
>
>--
>Tim Deegan <Tim.Deegan@citrix.com>
>Principal Software Engineer, XenServer Engineering
>Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)