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

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

On Tue, May 19, 2020 at 5:50 PM Roman Shaposhnik <roman@xxxxxxxxxx> wrote:
>
> On Tue, May 19, 2020 at 4:44 PM Tamas K Lengyel
> <tamas.k.lengyel@xxxxxxxxx> wrote:
> >
> > On Tue, May 19, 2020 at 11:23 AM Julien Grall <julien@xxxxxxx> wrote:
> > >
> > >
> > >
> > > On 19/05/2020 04:08, Tamas K Lengyel wrote:
> > > > On Mon, May 18, 2020 at 5:32 AM Julien Grall <julien@xxxxxxx> wrote:
> > > >>
> > > >> From: Julien Grall <jgrall@xxxxxxxxxx>
> > > >>
> > > >> 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.
>
> Stefano and I are testing the fix right now -- for now just set your
> Dom0 mem to less than 512m.

Actually seems to work after I recompiled the kernel and reinstalled
all kernel modules. Xen boots with 4gb RAM and dom0 boots with 2g:

xl info:
...
total_memory           : 3956
free_memory            : 1842

cat /proc/meminfo
MemTotal:        1963844 kB

I get an emergency shell during boot on the console complaining about
xenbr0 not coming up but if I just hit continue it boots fine and the
network is up. So AFAICT things are good.

Cheers,
Tamas