Re: [Xen-devel] XEN on R-CAR H3

[Oleksandr <olekstysh@xxxxxxxxx>]

Hi Julien


> > While I know that Xen does not deal with reserved area yet, we should 
> > have been
> > able to write in that region. We don't even reach that state as we 
> > can't get the
> > associated page.
> >
> > It might be possible that the p2m entry is overwritten when going 
> > through the DT
> > for mapping all the regions (see handle_device).
> Make sense.
>
>
> I have just made an experiment. I returned reserved nodes back in my 
> setup and got an fault, similar to what Amit had faced.
>
> (XEN) handle /memory@48000000
> (XEN)   Skip it (matched)
> (XEN) handle /reserved-memory
> (XEN) dt_irq_number: dev=/reserved-memory
> (XEN) /reserved-memory passthrough = 1 nirq = 0 naddr = 0
> (XEN) handle /reserved-memory/linux,lossy_decompress
> (XEN) dt_irq_number: dev=/reserved-memory/linux,lossy_decompress
> (XEN) /reserved-memory/linux,lossy_decompress passthrough = 1 nirq = 0 
> naddr = 1
> (XEN) DT: ** translation for device 
> /reserved-memory/linux,lossy_decompress **
> (XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
> (XEN) DT: translating address:<3> 00000000<3> 54000000<3>
> (XEN) DT: parent bus is default (na=2, ns=2) on /
> (XEN) DT: empty ranges; 1:1 translation
> (XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
> (XEN) DT: with offset: 54000000
> (XEN) DT: one level translation:<3> 00000000<3> 54000000<3>
> (XEN) DT: reached root node
> (XEN)   - MMIO: 0054000000 - 0057000000 P2MType=5
> (XEN) handle /reserved-memory/linux,adsp
> (XEN) dt_irq_number: dev=/reserved-memory/linux,adsp
> (XEN) /reserved-memory/linux,adsp passthrough = 1 nirq = 0 naddr = 1
> (XEN) DT: ** translation for device /reserved-memory/linux,adsp **
> (XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
> (XEN) DT: translating address:<3> 00000000<3> 57000000<3>
> (XEN) DT: parent bus is default (na=2, ns=2) on /
> (XEN) DT: empty ranges; 1:1 translation
> (XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
> (XEN) DT: with offset: 57000000
> (XEN) DT: one level translation:<3> 00000000<3> 57000000<3>
> (XEN) DT: reached root node
> (XEN)   - MMIO: 0057000000 - 0058000000 P2MType=5
> (XEN) handle /reserved-memory/linux,cma
> (XEN) dt_irq_number: dev=/reserved-memory/linux,cma
> (XEN) /reserved-memory/linux,cma passthrough = 1 nirq = 0 naddr = 1
> (XEN) DT: ** translation for device /reserved-memory/linux,cma **
> (XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
> (XEN) DT: translating address:<3> 00000000<3> 58000000<3>
> (XEN) DT: parent bus is default (na=2, ns=2) on /
> (XEN) DT: empty ranges; 1:1 translation
> (XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
> (XEN) DT: with offset: 58000000
> (XEN) DT: one level translation:<3> 00000000<3> 58000000<3>
> (XEN) DT: reached root node
> *(XEN)   - MMIO: 0058000000 - 0070000000 P2MType=5*
> (XEN) handle /reserved-memory/linux,multimedia
> (XEN) dt_irq_number: dev=/reserved-memory/linux,multimedia
> (XEN) /reserved-memory/linux,multimedia passthrough = 1 nirq = 0 naddr 
> = 1
> (XEN) DT: ** translation for device /reserved-memory/linux,multimedia **
> (XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
> (XEN) DT: translating address:<3> 00000000<3> 70000000<3>
> (XEN) DT: parent bus is default (na=2, ns=2) on /
> (XEN) DT: empty ranges; 1:1 translation
> (XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
> (XEN) DT: with offset: 70000000
> (XEN) DT: one level translation:<3> 00000000<3> 70000000<3>
> (XEN) DT: reached root node
> (XEN)   - MMIO: 0070000000 - 0080000000 P2MType=5
> (XEN) handle /mmngr
> (XEN) dt_irq_number: dev=/mmngr
> (XEN) /mmngr passthrough = 1 nirq = 0 naddr = 0
> (XEN) handle /mmngrbuf
> (XEN) dt_irq_number: dev=/mmngrbuf
> (XEN) /mmngrbuf passthrough = 1 nirq = 0 naddr = 0
> (XEN) handle /vspm_if
> (XEN) dt_irq_number: dev=/vspm_if
> (XEN) /vspm_if passthrough = 1 nirq = 0 naddr = 0
> (XEN) Allocating PPI 16 for event channel interrupt
> (XEN) Create hypervisor node
> (XEN) Create PSCI node
> (XEN) Create cpus node
> (XEN) Create cpu@0 (logical CPUID: 0) node
> (XEN) Create cpu@1 (logical CPUID: 1) node
> (XEN) Create cpu@2 (logical CPUID: 2) node
> (XEN) Create cpu@3 (logical CPUID: 3) node
> (XEN) Create memory node (reg size 4, nr cells 4)
> (XEN)   Bank 0: 0x60000000->0x70000000
> *(XEN) Loading zImage from 000000007a000000 to 
> 0000000060080000-0000000062080000*
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) Unable to copy the kernel in the hwdom memory
> (XEN) ****************************************
> (XEN)
> (XEN) Reboot in five seconds...
There is a question which worries me and likely other people as well. 
Which is "reserved memory area support in Xen". Some SoCs except 
application processors have some IPs (co-processors, dsps, codecs, 
whatever) which rely on a specific predefined memory regions, or even 
can work with these memory regions only...
Without this feature being supported, we won't be able to use IPs, whose 
firmware requires a predefined memory region to talk to an application 
processor, I am afraid.
One option comes to mind... I presume, the use of "iomem" property in 
domain config could allow us to assign 1:1 mapped region to that guest 
domain. Would it be a correct option?
What needs to be implementing it Xen, for example, to have a possibility 
to assign a particular reserved memory region(s) to a particular guest 
domain?
--
Regards,

Oleksandr Tyshchenko


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