Re: Xen 4.14.1 on RPI4: device tree generation failed

From: Elliott Mitchell <ehem+xen@m5p.com>
To: Tamas K Lengyel <tamas.k.lengyel@gmail.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: Xen 4.14.1 on RPI4: device tree generation failed
Date: Sun, 31 Jan 2021 17:59:27 -0800	[thread overview]
Message-ID: <YBdgf4KKcDn0SCOw@mattapan.m5p.com> (raw)
In-Reply-To: <CABfawhncPyDKy_G2Lz7MaEb_ZoPadHef7S7KAj-fbCbQq6YNGA@mail.gmail.com>

On Sun, Jan 31, 2021 at 06:50:36PM -0500, Tamas K Lengyel wrote:
> On Sun, Jan 31, 2021 at 6:33 PM Elliott Mitchell <ehem+undef@m5p.com> wrote:
> >
> > On Sun, Jan 31, 2021 at 02:06:17PM -0500, Tamas K Lengyel wrote:
> > > (XEN) Unable to retrieve address 0 for /scb/pcie@7d500000/pci@1,0/usb@1,0
> > > (XEN) Device tree generation failed (-22).
> >
> > > Does anyone have an idea what might be going wrong here? I tried
> > > building the dtb without using the dtb overlay but it didn't seem to
> > > do anything.
> >
> > If you go to line 1412 of the file xen/arch/arm/domain_build.c and
> > replace the "return res;" with "continue;" that will bypass the issue.
> > The 3 people I'm copying on this message though may wish to ask questions
> > about the state of your build tree.
> 
> I'll try that but it's a pretty hacky work-around ;)

Actually no, it simply causes Xen to ignore these entries.  The patch
I've got ready to submit to this list also adjusts the error message to
avoid misinterpretation, but does pretty well exactly this.

My only concern is whether it should ignore the entries only for Domain 0
or should always ignore them.

> > Presently the rpixen script is grabbing the RPF's 4.19 branch, dates
> > point to that last being touched last year.  Their tree is at
> > cc39f1c9f82f6fe5a437836811d906c709e0661c.
> 
> I've moved the Linux branch up to 5.10 because there had been a fair
> amount of work that went into fixing Xen on RPI4, which got merged
> into 5.9 and I would like to be able to build upstream everything
> without the custom patches coming with the rpixen script repo.

Please keep track of where your kernel source is checked out at since
there was a desire to figure out what was going on with the device-trees.

Including "console=hvc0 console=AMA0 console=ttyS0 console=tty0" in the
kernel command-line should ensure you get output from the kernel if it
manages to start (yes, Linux does support having multiple consoles at the
same time).

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