Re: [Xen-devel] [PATCH] Improve Dom0-less documentation

[Viktor Mitin <viktor.mitin.19@xxxxxxxxx>]

Hi,
On Tue, Jul 9, 2019 at 3:15 PM Julien Grall <julien.grall@xxxxxxx> wrote:
>
> Hi,
>
> On 7/9/19 8:23 AM, Viktor Mitin wrote:
> > On Mon, Jul 8, 2019 at 6:45 PM Julien Grall <julien.grall@xxxxxxx> wrote:
> >>
> >> Hello,
> > Hello Julien,
> >
> >>
> >> On 7/8/19 1:35 PM, Viktor Mitin wrote:
> >>> Updated configuration example according to arm64
> >>> and added more cases about known xl limitations.
> >>
> >> dom0less is not an arm64 specific feature. It also works on arm32, and
> >> therefore the docs should work for both cases. However...
> >>
> > There is one issue with it, please see below.
> >
> >>>
> >>> Signed-off-by: Viktor Mitin <viktor_mitin@xxxxxxxx>
> >>> ---
> >>>    docs/features/dom0less.pandoc | 29 +++++++++++++++++++++--------
> >>>    1 file changed, 21 insertions(+), 8 deletions(-)
> >>>
> >>> diff --git a/docs/features/dom0less.pandoc b/docs/features/dom0less.pandoc
> >>> index e076e3739e..961813696f 100644
> >>> --- a/docs/features/dom0less.pandoc
> >>> +++ b/docs/features/dom0less.pandoc
> >>> @@ -62,19 +62,19 @@ device tree adding a node under /chosen as follows:
> >>>
> >>>        domU1 {
> >>>            compatible = "xen,domain";
> >>> -        memory = <0x20000>;
> >>> +        memory = <0x0 0x20000>; >           cpus = 1;
> >>>            vpl011;
> >>>
> >>>            module@2000000 {
> >>>                compatible = "multiboot,kernel", "multiboot,module";
> >>> -            reg = <0x2000000 0xffffff>;
> >>> +            reg = <0x0 0x2000000 0x0 0xffffff>;
> >>
> >> ... nothing on arm64 impose #address-cells = 2 and #size-cells = 2. The
> >> problem here is the two properties are missing in the node domU1.
> >
> > The next issue was observed with arm64 (arm32 was not tested).
> > The reg properties inside 'module' nodes are ok either with additional '0x0'
> > or with #address-cells = 2 and #size-cells = 2.
> >
> > However, the 'memory' property does not work without additional '0x0'
> > and #address-cells = 2 and #size-cells = 2 don't affect it.
> > The next code fails without '0x0'. This was the reason why I added '0x0'
> > and not #address-cells = 2 and #size-cells = 2. Now it is clear that
> > we need to use
> > #address-cells and #size-cells anyway, however, I'm not sure about
> > memory property.
> > Should it be with extra zero anyway for both cases arm32 and arm64?
> >
> > memory = <0x0 0x20000>;
>
> Per the documentation (docs/misc/arm/device-tree/booting.txt):
>
> "- memory
>
> A 64-bit integer specifying the amount of kilobytes of RAM to
> allocate to the guest.
> "
>
> So memory is always a 64-bit integer and therefore is described using 2
> cells.

Clear. Will change memory property in example to be with extra 0x0.

Thanks

> Cheers,
>
> --
> Julien Grall

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