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RE: [PATCH v5 1/8] xen/arm: introduce static shared memory
- To: Julien Grall <julien@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Penny Zheng <Penny.Zheng@xxxxxxx>
- Date: Wed, 29 Jun 2022 08:40:01 +0000
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- Cc: Wei Chen <Wei.Chen@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Wed, 29 Jun 2022 08:40:17 +0000
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- Thread-topic: [PATCH v5 1/8] xen/arm: introduce static shared memory
Hi Julien
> -----Original Message-----
> From: Julien Grall <julien@xxxxxxx>
> Sent: Saturday, June 25, 2022 3:26 AM
> To: Penny Zheng <Penny.Zheng@xxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Wei Chen <Wei.Chen@xxxxxxx>; Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Bertrand Marquis <Bertrand.Marquis@xxxxxxx>;
> Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> Subject: Re: [PATCH v5 1/8] xen/arm: introduce static shared memory
>
> Hi Penny,
>
> I have looked at the code and I have further questions about the binding.
>
> On 20/06/2022 06:11, Penny Zheng wrote:
> > ---
> > docs/misc/arm/device-tree/booting.txt | 120
> ++++++++++++++++++++++++++
> > xen/arch/arm/Kconfig | 6 ++
> > xen/arch/arm/bootfdt.c | 68 +++++++++++++++
> > xen/arch/arm/include/asm/setup.h | 3 +
> > 4 files changed, 197 insertions(+)
> >
> > diff --git a/docs/misc/arm/device-tree/booting.txt
> > b/docs/misc/arm/device-tree/booting.txt
> > index 98253414b8..6467bc5a28 100644
> > --- a/docs/misc/arm/device-tree/booting.txt
> > +++ b/docs/misc/arm/device-tree/booting.txt
> > @@ -378,3 +378,123 @@ device-tree:
> >
> > This will reserve a 512MB region starting at the host physical address
> > 0x30000000 to be exclusively used by DomU1.
> > +
> > +Static Shared Memory
> > +====================
> > +
> > +The static shared memory device tree nodes allow users to statically
> > +set up shared memory on dom0less system, enabling domains to do
> > +shm-based communication.
> > +
> > +- compatible
> > +
> > + "xen,domain-shared-memory-v1"
> > +
> > +- xen,shm-id
> > +
> > + An 8-bit integer that represents the unique identifier of the shared
> memory
> > + region. The maximum identifier shall be "xen,shm-id = <0xff>".
>
> There is nothing in Xen that will ensure that xen,shm-id will match for all
> the
> nodes using the same region.
>
True, we actually do not use this field, adding it here to just be aligned with
Linux.
I could add a check in the very beginning when we parse the device tree.
I'll give more details to explain in which code locates.
> I see you write it to the guest device-tree. However there is a mismatch of
> the
> type: here you use an integer whereas the guest binding is using a string.
>
> Cheers,
>
> --
> Julien Grall
|
