Re: ARM:Booting xen on pine64 board

[Andre Przywara <andre.przywara@arm.com>]

Hi,

On 04/04/17 20:02, Stefano Stabellini wrote:
> Also CC'ing Andre that I think has a pine64.
> 
> On Tue, 4 Apr 2017, Stefano Stabellini wrote:
>> On Sat, 1 Apr 2017, bharat gohil wrote:
>>> Hello
>>
>> Hello Bharat, thanks for your email.
>>
>>
>>> I am trying to boot xen(debug build) on pine64 ARM64 based board but its hangs at following position,
>>>
>>> - UART enabled -
>>> - CPU 00000000 booting -
>>> - Current EL 00000008 -
>>> - Xen starting at EL2 -
>>> - Zero BSS -
>>> - Setting up control registers -
>>> - Turning on paging -
>>> - Ready -
>>> (XEN) Checking for initrd in /chosen
>>> (XEN) RAM: 0000000041000000 - 000000007fffffff
>>> (XEN)
>>> (XEN) MODULE[0]: 000000007e200000 - 000000007e202000 Device Tree
>>> (XEN) MODULE[1]: 000000007e400000 - 000000007ef46a00 Kernel       console=hvc0 ro root=/dev/mmcblk0p2 clk_ignore_unused rootwait
>>> (XEN)  RESVD[0]: 000000007e200000 - 000000007e202000
>>> (XEN)
>>> (XEN) Command line: dtuart=serial0 earlyprint loglvl=all conswitch=x dom0_mem=128M
>>> (XEN) Placing Xen at 0x000000007fc00000-0x000000007fe00000
>>> (XEN) Update BOOTMOD_XEN from 000000007fe00000-000000007fefad81 => 000000007fc00000-000000007fcfad81
>>> (XEN) Booting using Device Tree
>>> (XEN) Domain heap initialised
>>> (XEN) Platform: Generic System
>>> (XEN) Looking for dtuart at "serial0", options ""
>>>  Xen 4.9-unstable
>>> (XEN) Xen version 4.9-unstable (bgohil@) (aarch64-linux-gnu-gcc (Linaro GCC 6.2-2016.11) 6.2.1 20161016) debug=n  Tue Mar 28 16:12:32 IST 2017
>>> (XEN) Latest ChangeSet: Fri Mar 24 14:19:47 2017 +0100 git:5b08f85
>>> (XEN) Processor: 410fd034: "ARM Limited", variant: 0x0, part 0xd03, rev 0x4
>>> (XEN) 64-bit Execution:
>>> (XEN)   Processor Features: 0000000000002222 0000000000000000
>>> (XEN)     Exception Levels: EL3:64+32 EL2:64+32 EL1:64+32 EL0:64+32
>>> (XEN)     Extensions: FloatingPoint AdvancedSIMD
>>> (XEN)   Debug Features: 0000000010305106 0000000000000000
>>> (XEN)   Auxiliary Features: 0000000000000000 0000000000000000
>>> (XEN)   Memory Model Features: 0000000000001122 0000000000000000
>>> (XEN)   ISA Features:  0000000000011120 0000000000000000
>>> (XEN) 32-bit Execution:
>>> (XEN)   Processor Features: 00000131:00011011
>>> (XEN)     Instruction Sets: AArch32 A32 Thumb Thumb-2 Jazelle
>>> (XEN)     Extensions: GenericTimer Security
>>> (XEN)   Debug Features: 03010066
>>> (XEN)   Auxiliary Features: 00000000
>>> (XEN)   Memory Model Features: 10201105 40000000 01260000 02102211
>>> (XEN)  ISA Features: 02101110 13112111 21232042 01112131 00011142 00011121
>>> (XEN) Using PSCI-0.2 for SMP bringup
>>> (XEN) SMP: Allowing 4 CPUs
>>> (XEN) Generic Timer IRQ: phys=30 hyp=26 virt=27 Freq: 24000 KHz
>>> (XEN) GICv2 initialization:
>>> (XEN)         gic_dist_addr=0000000001c81000
>>> (XEN)         gic_cpu_addr=0000000001c82000
>>> (XEN)         gic_hyp_addr=0000000001c84000
>>> (XEN)         gic_vcpu_addr=0000000001c86000
>>> (XEN)         gic_maintenance_irq=25
>>> (XEN) GICv2: 224 lines, 4 cpus, secure (IID 0200143b).
>>> (XEN) Using scheduler: SMP Credit Scheduler (credit)
>>>
>>> but when I boot dtuart=<unknown value> say duart=xyz instead of dtuart=serial0, xen booted successfully but Dom0 crash while probing 'serial0' driver. 
>>>
>>> If I remove 'serial0' node from device tree, Dom0 boot successfully but unable to enter input into 'hvc' console. 
>>>
>>> what could be wrong here or missing something?
>>
>> What is your dom0 command line? Are you passing console=hvc0?
>>
>> It looks like pine64 is using an allwinner sun50i-uart, for which we
>> don't have a proper driver in Xen yet. That is probably the reason why
>> you can see some output from Xen, but you cannot type anything in later
>> in Dom0 (which is sent to Xen via the HVC console).  Please send a patch
>> to add a simple sun50i-uart driver (see xen/drivers/char/). Given that
>> both Xen and Linux are GPLv2, you can import code from Linux if you find
>> it appropriate.

The UART is exactly the same as in the other Allwinner SoCs, so there is
no need for a new UART driver.
Another issue inherited from the 32-bit Allwinner chips is that the
first four UARTs share a page, so they have to be blacklisted, as Xen
can't properly separate them.
You might want to look at xen/arch/arm/platforms/sunxi.c. Not sure if
this needs to be tied in arm64 somehow.

HTH,
Cheers,
Andre.

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