linux-kernel - Re: [RFC] PPC: MPIC: necessary readback after EOI?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1420650283.4961.52.camel@freescale.com>
Date:	Wed, 7 Jan 2015 11:04:43 -0600
From:	Scott Wood <scottwood@...escale.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	<linuxppc-dev@...ts.ozlabs.org>,
	Purcareata Bogdan <b43198@...escale.com>,
	<linux-kernel@...r.kernel.org>, Andreas Mohr <andi@...as.de>
Subject: Re: [RFC] PPC: MPIC: necessary readback after EOI?

On Wed, 2015-01-07 at 15:44 +0100, Benjamin Herrenschmidt wrote:
> On Mon, 2015-01-05 at 12:10 -0600, Scott Wood wrote:
> > It would have been nice if a code comment explained why it was doing the
> > readback...  I don't see any particular need to wait for EOI completion
> > here (unlike when masking).
> 
> The EOI is what causes the MPIC to drop it's EE output to the CPU, if the
> EOI is processed too slowly & asynchronously (posted write + 33Mhz MPIC)
> we observe cases of spurrious interrupts. We had some macs basically getting
> a spurrious irq for every MPIC interrupts...

Shouldn't reading INTACK be what causes the MPIC to drop its EE output?

-Scott


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/