Re: [RFC PATCH] xen/memory: Introduce a hypercall to provide unallocated space

[Julien Grall <julien@xxxxxxx>]

On 09/08/2021 22:18, Oleksandr wrote:
> On 09.08.21 23:45, Julien Grall wrote:
>
>
> Hi Julien

Hi Oleksandr,

> > On 09/08/2021 19:24, Oleksandr wrote:
> > > On 09.08.21 18:42, Julien Grall wrote:
> > > 1. If IOMMU is enabled for Dom0 -> provide holes found in Host DT as 
> > > safe ranges
> > > I would take into the account holes >= 1MB.
> > May I ask why 1MB?
> Nothing special, just thinking to not bother with small regions which 
> would not be too useful overall, but could bloat resulting reg property.
> Anyway, I would be ok with any sizes.
I was more interesting with the reasoning behind your choice rather than 
saying we want more.
I agree that we may want to skip smaller region. I am guess that an high 
number of small regions will also increase the bookeeping in Linux.
But I would probably suggest to align the safe region to a 2MB 
(superpage for 4KB page granularity) just because the backend (or even 
Xen) may be able to do some optimization there.
Cheers,

--
Julien Grall