From: Stefano Stabellini <sstabellini@kernel.org>
To: Elliott Mitchell <ehem+xen@m5p.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
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 18:06:26 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.2010131759270.10386@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <20201012213451.GA89158@mattapan.m5p.com>
On Mon, 12 Oct 2020, Elliott Mitchell wrote:
> On Mon, Oct 12, 2020 at 12:02:14PM -0700, Stefano Stabellini wrote:
> > On Sat, 10 Oct 2020, Julien Grall wrote:
> > > Therefore, I think the code should not try to find the STAO. Instead, it
> > > should check whether the SPCR table is present.
> >
> > Yes, that makes sense, but that brings me to the next question.
> >
> > SPCR seems to be required by SBBR, however, Masami wrote that he could
> > boot on a system without SPCR, which gets me very confused for two
> > reasons:
> >
> > 1) Why there is no SPCR? Isn't it supposed to be mandatory? Is it
> > because there no UART on Masami's system?
>
> 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 documentation is out of date.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.
next prev parent reply other threads:[~2020-10-14 1:06 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-26 20:55 [PATCH 0/4] xen/arm: Unbreak ACPI 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 12:41 ` [PATCH] xen: acpi: Hide UART address only if SPCR exists Masami Hiramatsu
2020-09-28 12:42 ` Masami Hiramatsu
2021-01-19 7:25 ` Elliott Mitchell
2021-01-20 18:05 ` Julien Grall
2020-09-28 13:00 ` [PATCH 0/4] xen/arm: Unbreak ACPI 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 [this message]
2020-10-14 1:37 ` Elliott Mitchell
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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