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Subject: Re: [PATCH] powerpc/8xx: Map a second 8M text page at startup when
 needed.
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
References: <27edd227d3b9dcda4e2ce7d00d9fddeb7a5520a1.1545241146.git.christophe.leroy@c-s.fr>
 <20181220082403.GA25436@infradead.org>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <49bf27a4-b0b1-27e1-78f1-a5d55c720d91@c-s.fr>
Date:   Thu, 20 Dec 2018 09:50:03 +0100
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Le 20/12/2018 à 09:24, Christoph Hellwig a écrit :
> On Thu, Dec 20, 2018 at 05:48:25AM +0000, Christophe Leroy wrote:
>> Some debug setup like CONFIG_KASAN generate huge
>> kernels with text size over the 8M limit.
>>
>> This patch maps a second 8M page when _einittext is over 8M.
> 
> Do we also need a check to generate a useful warning if we ever overflow
> the 16MB?
> 

I don't think any other platform does that (the 40x also maps 16Mb, 
book3s/601 maps 24Mb)

But why not, could do that in another patch.

Is there an easy way to get the link to fail when CONFIG_PIN_TLB_TEXT is 
set and _einittext is higher than 16Mb ?

Or should we just map up to 24Mb on the 8xx and consider we are on the 
safe side with that much ?

Christophe