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From: Elliott Mitchell <ehem+xen@m5p.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: Julien Grall <julien@xen.org>,
	Masami Hiramatsu <masami.hiramatsu@linaro.org>,
	xen-devel@lists.xenproject.org,
	Alex Benn??e <alex.bennee@linaro.org>,
	bertrand.marquis@arm.com, andre.przywara@arm.com,
	Julien Grall <jgrall@amazon.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [PATCH 0/4] xen/arm: Unbreak ACPI
Date: Tue, 13 Oct 2020 18:37:06 -0700
Message-ID: <20201014013706.GA98635@mattapan.m5p.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2010131759270.10386@sstabellini-ThinkPad-T480s>

On Tue, Oct 13, 2020 at 06:06:26PM -0700, Stefano Stabellini wrote:
> On Mon, 12 Oct 2020, Elliott Mitchell wrote:
> > I'm on different hardware, but some folks have setup Tianocore for it.
> > According to Documentation/arm64/acpi_object_usage.rst,
> > "Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT".  Yet when
> > booting a Linux kernel directly on the hardware it lists APIC, BGRT,
> > CSRT, DSDT, DBG2, FACP, GTDT, PPTT, RSDP, and XSDT.
> > 
> > I don't know whether Linux's ACPI code omits mention of some required
> > tables and merely panics if they're absent.  Yet I'm speculating the list
> > of required tables has shrunk, SPCR is no longer required, and the
> > documentation is out of date.  Perhaps SPCR was required in early Linux
> > ACPI implementations, but more recent ones removed that requirement?
> 
> I have just checked and SPCR is still a mandatory table in the latest
> SBBR specification. It is probably one of those cases where the firmware
> claims to be SBBR compliant, but it is not, and it happens to work with
> Linux.

Is meeting the SBBR specification supposed to be a requirement of running
Xen-ARM?

I don't seen any mention of such.
`find docs xen/arch/arm -type f -print0 | xargs -0 grep -eSBBR` produces
no output.

Perhaps you've been adding this as a presumptive requirement since
previously the only hardware capable of running Xen due to an
appropriately unlocked bootloader was SBBR compliant?  If so, it seems
time to either add this as an explicit requirement and document it, or
else remove this implicit requirement and start acting as such.

The Raspberry PI 4B has a UEFI implementation available which is based on
Tianocore.  No statement has been made of it qualifying as SBBR.  Yet it
is clearly mostly able to boot Xen, just this is exposing issues.


-- 
(\___(\___(\______          --=> 8-) EHM <=--          ______/)___/)___/)
 \BS (    |         ehem+sigmsg@m5p.com  PGP 87145445         |    )   /
  \_CS\   |  _____  -O #include <stddisclaimer.h> O-   _____  |   /  _/
8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445




  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-26 20:55 Julien Grall
2020-09-26 20:55 ` [PATCH 1/4] xen/acpi: Rework acpi_os_map_memory() and acpi_os_unmap_memory() Julien Grall
2020-09-28  8:18   ` Jan Beulich
2020-09-28  9:58     ` Julien Grall
2020-09-28 10:09       ` Jan Beulich
2020-09-28 10:39         ` Julien Grall
2020-10-10  9:49           ` Julien Grall
2020-10-10 10:04             ` Julien Grall
2020-09-29 11:10   ` Rahul Singh
2020-10-01  0:06   ` Stefano Stabellini
2020-10-01 15:09     ` Julien Grall
2020-09-26 20:55 ` [PATCH 2/4] xen/arm: acpi: The fixmap area should always be cleared during failure/unmap Julien Grall
2020-09-29 11:13   ` Rahul Singh
2020-10-01  0:30   ` Stefano Stabellini
2020-10-01 15:14     ` Julien Grall
2020-09-26 20:55 ` [PATCH 3/4] xen/arm: Check if the platform is not using ACPI before initializing Dom0less Julien Grall
2020-09-29 11:17   ` Rahul Singh
2020-09-30 23:26   ` Stefano Stabellini
2020-09-26 20:55 ` [PATCH 4/4] xen/arm: Introduce fw_unreserved_regions() and use it Julien Grall
2020-09-30 23:40   ` Stefano Stabellini
2020-10-01 15:34     ` Julien Grall
2020-09-27  1:47 ` [PATCH 0/4] xen/arm: Unbreak ACPI Elliott Mitchell
2020-09-29 15:28   ` Elliott Mitchell
2020-09-28  6:47 ` Masami Hiramatsu
2020-09-28 13:00   ` Masami Hiramatsu
2020-10-16 22:33     ` Xen-ARM EFI/ACPI problems (was: Re: [PATCH 0/4] xen/arm: Unbreak ACPI) Elliott Mitchell
2020-10-17  5:12       ` Elliott Mitchell
2020-10-08 18:39   ` [PATCH 0/4] xen/arm: Unbreak ACPI Elliott Mitchell
2020-10-09  9:39     ` Julien Grall
2020-10-09 14:22       ` Elliott Mitchell
2020-10-09 18:15         ` Julien Grall
2020-10-09 22:36           ` Elliott Mitchell
2020-10-09 21:49   ` Elliott Mitchell
2020-10-10 11:02   ` Julien Grall
2020-10-12 19:02     ` Stefano Stabellini
2020-10-12 21:34       ` Elliott Mitchell
2020-10-14  1:06         ` Stefano Stabellini
2020-10-14  1:37           ` Elliott Mitchell [this message]
2020-10-14 17:47             ` Julien Grall
2020-10-15 18:00               ` Stefano Stabellini
2020-10-14 17:44       ` Julien Grall
2020-09-29 11:10 ` Rahul Singh
2020-09-29 15:29 ` Alex Bennée
2020-09-29 17:07   ` Julien Grall
2020-09-29 21:11     ` Alex Bennée
2020-09-29 23:39       ` André Przywara
2020-09-30  8:51         ` Alex Bennée
2020-09-30 10:35         ` Julien Grall
2020-09-30  9:42       ` Julien Grall
2020-09-30 10:38         ` Alex Bennée
2020-09-30 11:10           ` Julien Grall

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