From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: christophe leroy <christophe.leroy@c-s.fr>
Cc: Scott Wood <scottwood@freescale.com>,
linuxppc-dev@lists.ozlabs.org, Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc 8xx: Loading kernels over 8Mbytes without CONFIG_PIN_TLB
Date: Sun, 08 Dec 2013 07:58:34 +1100 [thread overview]
Message-ID: <1386449914.21910.109.camel@pasglop> (raw)
In-Reply-To: <52A2ECE4.3050407@c-s.fr>
On Sat, 2013-12-07 at 10:39 +0100, christophe leroy wrote:
> Function setup_initial_memory_limit() in mm/init_32.c defines the
> limits
> based on the parameters given by the bootloader.
> As far as I know, the 8xx doesn't do speculative access just because
> an area is loaded in a TLB Entry.
Speculative accesses are ... speculative :-) The address used for such
an access can be anything really. So yes, architecturally, powerpc
processors can access *anything* speculatively just because there's a
valid non-garded translation.
Whether the 8xx does it at all, I don't know. 44x originally did but
that was so buggy that we had to force G on all mappings (until later
versions of the core just burned the feature out). Pretty much all other
powerpc's do it.
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: christophe leroy <christophe.leroy@c-s.fr>
Cc: Scott Wood <scottwood@freescale.com>,
Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc 8xx: Loading kernels over 8Mbytes without CONFIG_PIN_TLB
Date: Sun, 08 Dec 2013 07:58:34 +1100 [thread overview]
Message-ID: <1386449914.21910.109.camel@pasglop> (raw)
In-Reply-To: <52A2ECE4.3050407@c-s.fr>
On Sat, 2013-12-07 at 10:39 +0100, christophe leroy wrote:
> Function setup_initial_memory_limit() in mm/init_32.c defines the
> limits
> based on the parameters given by the bootloader.
> As far as I know, the 8xx doesn't do speculative access just because
> an area is loaded in a TLB Entry.
Speculative accesses are ... speculative :-) The address used for such
an access can be anything really. So yes, architecturally, powerpc
processors can access *anything* speculatively just because there's a
valid non-garded translation.
Whether the 8xx does it at all, I don't know. 44x originally did but
that was so buggy that we had to force G on all mappings (until later
versions of the core just burned the feature out). Pretty much all other
powerpc's do it.
Cheers,
Ben.
next prev parent reply other threads:[~2013-12-07 20:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-27 11:04 [PATCH] powerpc 8xx: Loading kernels over 8Mbytes without CONFIG_PIN_TLB Christophe Leroy
2013-11-27 11:04 ` Christophe Leroy
2013-12-06 19:09 ` Scott Wood
2013-12-06 19:09 ` Scott Wood
2013-12-07 9:39 ` christophe leroy
2013-12-07 9:39 ` christophe leroy
2013-12-07 20:58 ` Benjamin Herrenschmidt [this message]
2013-12-07 20:58 ` Benjamin Herrenschmidt
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