Re: xen4.13 on raspberry4B use Domain U to control GPIO device

[Julien Grall <julien@xxxxxxx>]

Hello,

+Stefano

On 29/08/2021 15:43, 樊心昊 wrote:
> Hello everyone:
>      I'm trying use Domain U to control GPIO,but I can't find a way to 
> share bcm2835-gpiomem or gpiomem for Domain U.
>      When I had written xl.cfg file, like this
>
>     kernel = "/home/aston/GUEST_Domain/guest_image"
>     cmdline = "console=hvc0 earlyprintk=xen sync_console root=/dev/xvda"
>     memory = "256"
>     name = "rpi4-xen-guest"
>     vcpus = 1
>     serial="pty"
>     disk = [ 'phy:/dev/loop0,xvda,w' ]
>     vif=[ 'mac=00:11:22:66:88:22,bridge=xenbr0,type=netfront', ] 
>
>       device_tree = "/boot/bcm2711-rpi-4-b.dtb"
>
>     dtdev = [ "/soc/gpiomem@7e200000" ]
>
>     iomem = [ "0x7e200000,1@0x1000" ] 
>
>     ioports=['0x5'] 
>
> It will result in anerror，like this
>
> iomem = [ "0x7e200000,1@0x1000" ]   cause:
>
>     libxl: error: libxl_create.c:1498:domcreate_launch_dm: Domain
>     1:failed give domain access to iomem range 7e200000-7e200000:
>     Operation not permitted
The option 'iomem' takes frame numbers in arguments. If I am not 
mistaken 0x7e200000 is an address, so you would want to use 0x7e200.
Similar the bits after @ if a guest frame number. Can you confirm you 
want to map at 0x1000000?
>     (XEN) gnttab_mark_dirty not implemented yet
>
>
>   device_tree = "/boot/bcm2711-rpi-4-b.dtb"
>   dtdev = [ "/soc/gpiomem@7e200000" ]
> cause
>
>     libxl: error: libxl_create.c:980:libxl__domain_config_setdefault:
>     passthrough not supported on this platform
dtdev is used to configure devices protected by an IOMMU. I would be 
surprised if the GPIO is behind an IOMMU. Can you confirm it?
Note that in this case you need to ensure that you device is not doing 
any DMA (this would be insecure and broken because guest are have a 
different view of the memory).
> ioports=['0x5']
> cause
>
>     libxl: error: libxl_create.c:1467:domcreate_launch_dm: Domain
>     2:failed give domain access to ioports 5-5: Operation not supported
The option ioport is an x86 specific option. What are you attempting to 
do with this option?
Cheers,

--
Julien Grall