Re: [Xen-devel] [PATCH v2 0/2] Raspberry Pi 4 support

[Stewart Hildebrand <Stewart.Hildebrand@dornerworks.com>]

On Wednesday, July 31, 2019 8:32 AM, Andre Przywara <andre.przywara@arm.com> wrote:
>On Mon, 29 Jul 2019 09:19:18 -0400
>Stewart Hildebrand <stewart.hildebrand@dornerworks.com> wrote:
>
>Hi,
>
>> This is a series to enable UART console for Raspberry Pi 4. Note that I'm relying on the firmware to initialize the UART (i.e. enable_uart=1 in config.txt), since full UART initialization on this platform requires accessing some registers outside the range specified in the brcm,bcm2835-aux-uart node.
>>
>> I have been able to get Xen+dom0+domUs booting. Tested with Xen 4.12 and 4.13-unstable (b4c8a27d5b)
>
>Mmmh, did that really work for you? I needed the next commit in staging as well:
>commit ead6b9f78355e8d366e0c80c4a73fa7fbd6d26cc
>Author: Andrii Anisov <andrii_anisov@epam.com>
>Date:   Thu Jul 18 16:22:20 2019 +0300
>
>    xen/arm: cpuerrata: Align a virtual address before unmap
>
>Otherwise Xen would crash before even considering Dom0.

Hmm... Yes. I did not have Andrii's patch included in my tests. I tested in 4.13-unstable (b4c8a27d5b) and on 4.12 (604ee1116d3e), it booted into Xen+dom0. Now that I'm thinking about it, the domU test may have only been on 4.12, not on 4.13-unstable.

>With Andrii's patch, your two patches and Stefano's resmem series I was able to at least run Xen till it was looking for Dom0, from U-
>Boot, with ATF (providing PSCI).

I'm not using ATF/U-Boot, and I've limited system RAM to total_mem=1024 in config.txt (even though I have the 4GB model) due to some DMA/driver issues (SD card, PCIe, etc) with the 64-bit RPi kernel. I also did not have Stefano's reserved-memory series applied in any test.

The following logs are a from couple of test runs from 4.13-unstable on Sun Jul 28:

(XEN) RAM: 0000000000000000 - 000000003b3fffff
(XEN) 
(XEN) MODULE[0]: 000000002eff5f00 - 000000002effff49 Device Tree 
(XEN) MODULE[1]: 0000000000480000 - 0000000001400000 Kernel      
(XEN)  RESVD[0]: 0000000000000000 - 0000000000001000
...
(XEN) Allocating 1:1 mappings totalling 512MB for dom0:
(XEN) BANK[0] 0x00000010000000-0x00000028000000 (384MB)
(XEN) BANK[1] 0x00000030000000-0x00000038000000 (128MB)

Curiously, in another test with total_mem=1536, Xen happened to allocate memory for dom0 in a different way. I am noticing that the RPi firmware carved out a hole in RAM for me in this case.

(XEN) RAM: 0000000000000000 - 000000003b3fffff
(XEN) RAM: 0000000040000000 - 000000005fffffff
(XEN) 
(XEN) MODULE[0]: 000000002eff5f00 - 000000002effff55 Device Tree 
(XEN) MODULE[1]: 0000000000480000 - 0000000001400000 Kernel      
(XEN)  RESVD[0]: 0000000000000000 - 0000000000001000
...
(XEN) Allocating 1:1 mappings totalling 512MB for dom0:
(XEN) BANK[0] 0x00000010000000-0x00000020000000 (256MB)
(XEN) BANK[1] 0x00000040000000-0x00000050000000 (256MB)

Stew

>There seems to be some hiccup in the reserved-memory code in U-Boot, where U-Boot tries to use the already region, but that's an
>independent matter.
>
>Cheers,
>Andre.
>
>> and Linux 4.19.y (Raspberry Pi linux tree + a couple of patches). Please see [1] for build instructions and limitations.
>>
>> New in v2:
>> * Drop early printk alias
>> * Set reg-shift and reg-io-width in the Xen driver
>> * Blacklist other aux peripherals in platform settings (spi1, spi2, and a couple of base aux registers)
>>
>> Thanks,
>> Stewart Hildebrand
>> DornerWorks, Ltd
>>
>> [1] https://github.com/dornerworks/xen-rpi4-builder
>>
>> Stewart Hildebrand (2):
>>   ns16550: Add compatible string for Raspberry Pi 4
>>   xen/arm: platform: Add Raspberry Pi platform
>>
>>  xen/arch/arm/platforms/Makefile            |  1 +
>>  xen/arch/arm/platforms/brcm-raspberry-pi.c | 55 ++++++++++++++++++++++
>>  xen/drivers/char/ns16550.c                 |  7 +++
>>  3 files changed, 63 insertions(+)
>>  create mode 100644 xen/arch/arm/platforms/brcm-raspberry-pi.c
>>


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