From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: John David Anglin <dave.anglin@bell.net>, Sam James <sam@gentoo.org>
Cc: linux-parisc@vger.kernel.org, hppa@gentoo.org
Subject: Re: Recurring INEQUIVALENT ALIASES issues and userland corruption/crashes
Date: Tue, 19 Apr 2022 17:52:11 -0400 [thread overview]
Message-ID: <137e0b6f4dcaceafeac4b1ecfa30e4249939028d.camel@HansenPartnership.com> (raw)
In-Reply-To: <7a25a890-461b-0ba4-0b77-57d639de0007@bell.net>
On Tue, 2022-04-19 at 17:29 -0400, John David Anglin wrote:
> We know that the PDC call to determine cache
> characteristics indicates that the alias boundary on PA8800/PA8900 is
> larger than 16 MB.
Sorry, late to the party. What the PDC tells you is unreliable.
However, the Architecture guide Appendix F says "These rules provide
offset aliasing on 16 Mbyte boundaries, with optional support for
offset aliasing on smaller power of two sized boundaries, and either
restricted or unlimited space aliasing."
So unless someone has an update to the architecture guide, 16MB as a
cache stride is architecturally required to work. The tmpalias code in
pacache.S is predicated on an assurance by the old HP chip designers
that no chip was released with a cache stride greater than 4MB, meaning
we could safely relax the 16MB architectural rules down to 4MB.
James
next prev parent reply other threads:[~2022-04-19 21:52 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 17:52 Recurring INEQUIVALENT ALIASES issues and userland corruption/crashes Sam James
2022-03-22 18:14 ` Helge Deller
2022-03-22 18:30 ` John David Anglin
2022-03-22 19:47 ` Sam James
2022-03-22 18:19 ` John David Anglin
2022-03-22 19:37 ` Sam James
2022-03-22 19:52 ` Helge Deller
2022-03-22 20:42 ` Sam James
2022-03-22 21:04 ` John David Anglin
[not found] ` <73bf3336-9207-ba0e-1950-8cb1b7d6adc3@bell.net>
2022-03-22 20:29 ` John David Anglin
2022-03-22 20:43 ` Sam James
2022-03-22 23:59 ` John David Anglin
2022-04-05 21:13 ` John David Anglin
2022-04-12 5:18 ` Sam James
2022-04-12 12:27 ` John David Anglin
2022-04-12 13:20 ` John David Anglin
2022-04-12 23:45 ` Sam James
2022-04-19 19:52 ` Sam James
2022-04-19 21:29 ` John David Anglin
2022-04-19 21:52 ` James Bottomley [this message]
2022-04-20 0:11 ` John David Anglin
2022-04-23 20:33 ` John David Anglin
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