Re: [PATCH for-4.14 0/3] Remove the 1GB limitation on Rasberry Pi 4

[Tamas K Lengyel <tamas.k.lengyel@gmail.com>]

On Tue, May 19, 2020 at 11:23 AM Julien Grall <julien@xen.org> wrote:
>
>
>
> On 19/05/2020 04:08, Tamas K Lengyel wrote:
> > On Mon, May 18, 2020 at 5:32 AM Julien Grall <julien@xen.org> wrote:
> >>
> >> From: Julien Grall <jgrall@amazon.com>
> >>
> >> Hi all,
> >>
> >> At the moment, a user who wants to boot Xen on the Raspberry Pi 4 can
> >> only use the first GB of memory.
> >>
> >> This is because several devices cannot DMA above 1GB but Xen doesn't
> >> necessarily allocate memory for Dom0 below 1GB.
> >>
> >> This small series is trying to address the problem by allowing a
> >> platform to restrict where Dom0 banks are allocated.
> >>
> >> This is also a candidate for Xen 4.14. Without it, a user will not be
> >> able to use all the RAM on the Raspberry Pi 4.
> >>
> >> This series has only be slighlty tested. I would appreciate more test on
> >> the Rasbperry Pi 4 to confirm this removing the restriction.
> >
> > Hi Julien,
>
> Hi,
>
> > could you post a git branch somewhere? I can try this on my rpi4 that
> > already runs 4.13.
>
> I have pushed a branch based on unstable and the v2 of the series:
>
> git://xenbits.xen.org/people/julieng/xen-unstable.git
>
> branch arm-dma/v2
>

I've updated my image I built with
https://github.com/tklengyel/xen-rpi4-builder a while ago and I've
defined 2048m as total_mem and Xen seems to be booting fine and passes
execution to dom0. With 512m being set as the Xen cmdline for dom0_mem
it was working. When I increased the mem for dom0 the boot is now
stuck at:

[    1.427788] of_cfs_init
[    1.429667] of_cfs_init: OK
[    1.432561] clk: Not disabling unused clocks
[    1.437239] Waiting for root device /dev/mmcblk0p2...
[    1.451599] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[    1.458156] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    1.464729] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    1.472804] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[    1.479370] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    1.546902] random: fast init done
[    1.564590] mmc1: new high speed SDIO card at address 0001

Could this be because the DTB I compiled from a fresh checkout of
https://github.com/raspberrypi/linux.git branch rpi-4.19.y whereas the
kernel itself is from a checkout ~5 months ago? I guess that must be
the cause because even if I decrease the dom0_mem to 512m it still
gets stuck at the same spot whereas it was booting fine before.

Tamas