From: Jan Beulich <jbeulich@suse.com>
To: Igor Druzhinin <igor.druzhinin@citrix.com>
Cc: xen-devel@lists.xenproject.org, andrew.cooper3@citrix.com,
roger.pau@citrix.com, wl@xen.org, iwj@xenproject.org
Subject: Re: [PATCH v2] hvmloader: flip "ACPI data" to "ACPI NVS" type for ACPI table region
Date: Fri, 16 Oct 2020 08:34:24 +0200 [thread overview]
Message-ID: <ca9ba430-f5d8-f520-e7db-3e8d41cd7d9b@suse.com> (raw)
In-Reply-To: <1602808763-22396-1-git-send-email-igor.druzhinin@citrix.com>
On 16.10.2020 02:39, Igor Druzhinin wrote:
> ACPI specification contains statements describing memory marked with regular
> "ACPI data" type as reclaimable by the guest. Although the guest shouldn't
> really do it if it wants kexec or similar functionality to work, there
> could still be ambiguities in treating these regions as potentially regular
> RAM.
>
> One such example is SeaBIOS which currently reports "ACPI data" regions as
> RAM to the guest in its e801 call. Which it might have the right to do as any
> user of this is expected to be ACPI unaware. But a QEMU bootloader later seems
> to ignore that fact and is instead using e801 to find a place for initrd which
> causes the tables to be erased. While arguably QEMU bootloader or SeaBIOS need
> to be fixed / improved here, that is just one example of the potential problems
> from using a reclaimable memory type.
>
> Flip the type to "ACPI NVS" which doesn't have this ambiguity in it and is
> described by the spec as non-reclaimable (so cannot ever be treated like RAM).
>
> Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
next prev parent reply other threads:[~2020-10-16 6:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-16 0:39 [PATCH v2] hvmloader: flip "ACPI data" to "ACPI NVS" type for ACPI table region Igor Druzhinin
2020-10-16 6:34 ` Jan Beulich [this message]
2020-10-16 13:34 ` Sander Eikelenboom
2020-10-16 13:48 ` Igor Druzhinin
2020-10-16 15:13 ` Jan Beulich
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