linux-kernel - Re: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA banks listed in APEI HEST CMC

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Date:	Fri, 21 Jun 2013 09:34:19 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:	tony.luck@...el.com, ananth@...ibm.com, masbock@...ux.vnet.ibm.com,
	lcm@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, ying.huang@...el.com
Subject: Re: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA
 banks listed in APEI HEST CMC

On Fri, Jun 21, 2013 at 02:52:25AM +0530, Naveen N. Rao wrote:
> Exactly, but mce_poll_banks also doesn't have bits set for banks on
> which CMCI is enabled.
>
> Let's say we have a cpu with 2 banks (not shared), none of which work
> in FF mode. Both these banks support CMCI, so mce_poll_banks won't
> have these bits set.
>
> On cpu offline, we call cmci_clear() which disables CMCI on these two
> banks before offlining it. When this cpu is brought online again, we
> call cmci_discover() which sees that mce_poll_banks doesn't have these
> two banks enabled and will skip enabling CMCI thinking these are in
> FF.

Hmm, mce_intel has yet another bitfield - mce_banks_owned. (Btw, this is
why I have a problem with adding yet another bitfield).

The way I understand it is, if a bit is set in the owned bitfield, those
banks belong to CMCI and are not polled.

Now, can we use both mce_banks_owned and mce_poll_banks? If a bit in
both bifields is cleared, the corresponding bank is not polled *and* is
not owned by CMCI => it is in FF mode.

Makes sense?

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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