Hi Julien > -----Original Message----- > From: Julien Grall <jul...@xen.org> > Sent: Saturday, June 25, 2022 3:26 AM > To: Penny Zheng <penny.zh...@arm.com>; xen-devel@lists.xenproject.org > Cc: Wei Chen <wei.c...@arm.com>; Stefano Stabellini > <sstabell...@kernel.org>; Bertrand Marquis <bertrand.marq...@arm.com>; > Volodymyr Babchuk <volodymyr_babc...@epam.com> > 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
