Re: When would Xen reset page access rights for a non-migrating guest?

[Razvan Cojocaru <rzvncj@gmail.com>]

Hello,

> Tmem is not compiled into Xen for XenServer.

Well, it is compiled into Xen for XenServer:

$ find . -name "*tmem*.o"
./tools/libxc/xc_tmem.o
./xen/common/tmem.o
./xen/common/compat/tmem_xen.o
./xen/common/tmem_xen.o

Maybe it's not active.

> What sort of quirks are you on about?

You need to disable seabios for one. There are certain instructions that
are being emulated by the vanilla Xen but emulation code for them is
commented out with XenServer's Xen. I assume other things as well.

>> Running xl does show tmem parameters:
>>
>> # xl | grep tmem
>>   tmem-list           List tmem pools
>>   tmem-freeze         Freeze tmem pools
>>   tmem-thaw           Thaw tmem pools
>>   tmem-set            Change tmem settings
>>   tmem-shared-auth    De/authenticate shared tmem pool
>>   tmem-freeable       Get information about how much freeable memory
>>                       (MB) is in-use by tmem
> 
> Trying to use any of those should result in an -ENOSYS.

OK, I'm sure you're right. Will try it as soon as I get a chance.

> Given the default setup, there will almost certainly be PoD, and
> probably also be some Ballooning in there.

Sounds good, will look into that.


Thanks,
Razvan