Re: [Xen-devel] REGRESSION: Xen 4.13 RC5 fails to bootstrap Dom0 on ARM

[Stefano Stabellini <sstabellini@kernel.org>]

On Tue, 17 Dec 2019, Roman Shaposhnik wrote:
> On Tue, Dec 17, 2019 at 10:30 AM Stefano Stabellini
> <sstabellini@kernel.org> wrote:
> >
> > On Tue, 17 Dec 2019, Julien Grall wrote:
> > > Hi,
> > >
> > > On 17/12/2019 04:39, Roman Shaposhnik wrote:
> > > > On Mon, Dec 16, 2019 at 6:55 PM Stefano Stabellini
> > > > <sstabellini@kernel.org> wrote:
> > > > > On Mon, 16 Dec 2019, Roman Shaposhnik wrote:
> > > > > If I sum all the memory sizes together I get 0x3ddfd000 which is 990M.
> > > > > If so, I wonder how you could boot succesfully with dom0_mem=1024M even
> > > > > on Xen 4.12... :-?
> > > >
> > > > That is a very interesting observation indeed! I actually don't
> > > > remember where that device tree came from, but I think it was from one
> > > > of the Linaro sites.
> > >
> > > This is mostly likely because of:
> > >
> > > commit 6341a674573f1834f083f0ab0f5b36b075f9e02e
> > > Author: Julien Grall <julien.grall@arm.com>
> > > Date:   Wed Aug 21 22:42:31 2019 +0100
> > >
> > >     xen/arm: domain_build: Don't continue if unable to allocate all dom0 banks
> > >
> > >     Xen will only print a warning if there are memory unallocated when using
> > >     1:1 mapping (only used by dom0). This also includes the case where no
> > >     memory has been allocated.
> > >
> > >     It will bring to all sort of issues that can be hard to diagnostic for
> > >     users (the warning can be difficult to spot or disregard).
> > >
> > >     If the users request 1GB of memory, then most likely they want the exact
> > >     amount and not 512MB. So panic if all the memory has not been allocated.
> > >
> > >     After this change, the behavior is the same as for non-1:1 memory
> > >     allocation (used by domU).
> > >
> > >     At the same time, reflow the message to have the format on a single
> > >     line.
> > >
> > >     Signed-off-by: Julien Grall <julien.grall@arm.com>
> > >     Acked-by: Stefano Stabellini <sstabellini@kernel.org>
> >
> > Ah! Roman, could you please post the full boot log of a successful 4.12
> > boot?
> >
> > If it has a "Failed to allocate requested dom0 memory" message, then we
> > know what the issue is.
> 
> Aha! Our messages seems to have crossed ;-) Full log is attached and
> yes -- that's
> the problem indeed.
> 
> So at least that mystery is solved. But I'm still not able to get to a
> full 1G of memory
> even with your update to the device tree file. Any chance you can send me the
> device tree file that works for you?

I didn't try on real hardware, I only tried on QEMU with a similar
configuration. I went back and check the HiKey device tree I used and it
is the same as yours (including the ramoops reserved-memory error).

Apparently there are 1G and 2G variants of the HiKey, obviously both
yours and my device tree are for the 1G variant. I try to dig through
the docs but couldn't find the details of the 2G variant. I cannot find
anywhere the memory range for the top 1G of memory not even on the
LeMaker docs! :-/

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