Re: [PATCH v4 03/10] tools/libxl: add vmtrace_pt_size parameter

[Michał Leszczyński <michal.leszczynski@xxxxxxx>]

----- 2 lip 2020 o 11:00, Roger Pau Monné roger.pau@xxxxxxxxxx napisał(a):

> On Tue, Jun 30, 2020 at 02:33:46PM +0200, Michał Leszczyński wrote:
>> diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
>> index 59bdc28c89..7b8289d436 100644
>> --- a/xen/include/public/domctl.h
>> +++ b/xen/include/public/domctl.h
>> @@ -92,6 +92,7 @@ struct xen_domctl_createdomain {
>>      uint32_t max_evtchn_port;
>>      int32_t max_grant_frames;
>>      int32_t max_maptrack_frames;
>> +    uint8_t vmtrace_pt_order;
> 
> I've been thinking about this, and even though this is a domctl (so
> not a stable interface) we might want to consider using a size (or a
> number of pages) here rather than an order. IPT also supports
> TOPA mode (kind of a linked list of buffers) that would allow for
> sizes not rounded to order boundaries to be used, since then only each
> item in the linked list needs to be rounded to an order boundary, so
> you could for example use three 4K pages in TOPA mode AFAICT.
> 
> Roger.

In previous versions it was "size" but it was requested to change it
to "order" in order to shrink the variable size from uint64_t to
uint8_t, because there is limited space for xen_domctl_createdomain
structure.

How should I proceed?

Best regards,
Michał Leszczyński
CERT Polska