Re: [Xen-devel] [PATCH 4/4] iommu: add rmrr Xen command line option for extra rmrrs

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Tuesday, June 02, 2015 2:30 PM
> 
> >>> On 02.06.15 at 02:39, <kevin.tian@xxxxxxxxx> wrote:
> >>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: Monday, June 01, 2015 5:17 PM
> >> >>> On 01.06.15 at 08:30, <kevin.tian@xxxxxxxxx> wrote:
> >> >>  From: elena.ufimtseva@xxxxxxxxxx
> >> >> --- a/docs/misc/xen-command-line.markdown
> >> >> +++ b/docs/misc/xen-command-line.markdown
> >> >> @@ -1185,6 +1185,19 @@ Specify the host reboot method.
> >> >>  'efi' instructs Xen to reboot using the EFI reboot call (in EFI mode by
> >> >>   default it will use that method first).
> >> >>
> >> >> +### rmrr
> >> >> +> '=
> >> start<-end>=[s1]bdf1[,[s1]bdf2[,...]];start<-end>=[s2]bdf1[,[s2]bdf2[,...]]
> >> >> +
> >> >> +Define RMRRs units that are missing from ACPI table along with device
> >> >> +they belong to and use them for 1:1 mapping. End addresses can be
> >> omitted
> >> >> +and one page will be mapped. The ranges are inclusive when start and
> >> end
> >> >> +are specified.If segement of the first device is not specified, segment
> zero
> >> >> will be used.
> >> >> +If other segments are not specified, first device segment will be used.
> >> >> +If segments are specified for every device and not equal, an error will
> be
> >> >> reported.
> >> >
> >> > Since you only allow devices under same segment for a given rmrr range,
> >> > would it be simpler to enforce that explicitly in the format? e.g.:
> >> >
> >> > = start<-end>=[s1]bdf1[,bdf2[,...]];
> >>
> >> While that might simplify the code, I think it's better to allow the
> >> user to specify canonical device coordinates, which would include
> >> a segment number. Plus ...
> >>
> >> > Then you don't need to verify whether segment in later bdfs is specified
> and
> >> > different from 1st bdf.
> >>
> >> ... verification could not be dropped, unless we altered parse_pci()
> >> to have a way to not accept a segment number at all.
> >>
> >
> > Is that already the case? otherwise below comment and earlier patch 3/4 is
> > meaningless:
> >
> > + If other segments are not specified, first device segment will be used.
> 
> That function currently allows (but doesn't require) the segment
> part to be missing. Other than what we would need here it implies
> segment 0 if not specified.
> 

I see. Thanks

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel