Subject: Re: [PATCH] powerpc 8xx: Loading kernels over 8Mbytes without CONFIG_PIN_TLB

From: christophe leroy <[email-masked]>
Date: Sat, 07 Dec 2013 10:39:48 +0100

Le 06/12/2013 20:09, Scott Wood a écrit :
> On Wed, 2013-11-27 at 12:04 +0100, Christophe Leroy wrote:
>> Today, the only way to load kernels whose size is greater than 8Mbytes is to
>> activate CONFIG_PIN_TLB. Otherwise, the physical memory initially mapped is
>> limited to 8Mbytes. This patch sets up 24 Mbytes of initial memory regardless
>> of whether CONFIG_PIN_TLB is active or not. It allows to load "big" kernels
>> (for instance when activating CONFIG_LOCKDEP_SUPPORT) without having
>> to activate CONFIG_PIN_TLB.
> So, what happens on boards with less than 24M memory present?  Even if
> you avoid explicitly referencing those addresses, what if there is a
> speculative access -- or does 8xx not do that?
>
> -Scott
>

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.

Christophe

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