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Date: Fri, 24 May 2024 22:07:40 +0200
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Subject: Re: [PATCH] riscv: Don't use hugepage mappings for vmemmap if it's
 not supported
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To: Nam Cao <namcao@linutronix.de>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
 Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Alexandre Ghiti <alexghiti@rivosinc.com>, linux-riscv@lists.infradead.org,
 linux-kernel@vger.kernel.org
References: <20240508173116.2866192-1-namcao@linutronix.de>
 <43829e94-98ae-46a4-a3e6-dbabbe94d7c1@ghiti.fr>
 <20240508184641.WP8ok_Hg@linutronix.de>
From: Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20240508184641.WP8ok_Hg@linutronix.de>
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X-GND-Sasl: alex@ghiti.fr

Hi Nam,

On 08/05/2024 20:46, Nam Cao wrote:
> On Wed, May 08, 2024 at 08:22:43PM +0200, Alexandre Ghiti wrote:
>> Hi Nam,
> Hi Alex,
>
>>> Commit ff172d4818ad ("riscv: Use hugepage mappings for vmemmap") broke XIP
>>> kernel, because huge pages are not supported on XIP kernel.
>> I don't understand why XIP kernels can't support huge vmalloc mappings,
> Me neither.
>
>> so I
>> think the right fix would be to enable such mappings on XIP. WDYT?
> I agree that is the ideal solution. But I don't want to send any new
> feature to the stable trees (stable folks may even reject such patch).
> So I intend that to be in another patch.


I have been thinking about that, and I actually think that the real fix 
is enabling huge vmalloc mappings for XIP as it was an oversight/mistake 
in the first place. On 64-bit kernels, there are no reasons we can't use 
PMD mappings for vmalloc. So I'd rather not go with this fix.

Thanks,

Alex


>
> Best regards,
> Nam