linux-kernel - Re: [PATCH] powerpc/8xx: Map a second 8M text page at startup when needed.

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Message-ID: <49bf27a4-b0b1-27e1-78f1-a5d55c720d91@c-s.fr>
Date:   Thu, 20 Dec 2018 09:50:03 +0100
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] powerpc/8xx: Map a second 8M text page at startup when
 needed.



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