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Date: Wed, 10 Apr 2024 17:30:54 +0200
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Subject: Re: [PATCH v3 1/2] riscv: nommu: remove PAGE_OFFSET hardcoding
To: Jisheng Zhang <jszhang@kernel.org>,
 Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt
 <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Daniel Lezcano <daniel.lezcano@linaro.org>,
 Thomas Gleixner <tglx@linutronix.de>,
 Samuel Holland <samuel.holland@sifive.com>, Conor Dooley <conor@kernel.org>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20240410142347.964-1-jszhang@kernel.org>
 <20240410142347.964-2-jszhang@kernel.org>
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From: =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= <cleger@rivosinc.com>
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On 10/04/2024 16:23, Jisheng Zhang wrote:
> Currently, PAGE_OFFSET is hardcoded as 0x8000_0000, it works fine since
> there's only one nommu platform in the mainline. However, there are
> many cases where the (S)DRAM base address isn't 0x8000_0000, so remove
> the hardcoding value, and introduce DRAM_BASE which will be set by

Hi Jisheng,

Typo: s/harcoding/hardcoded

> users during configuring. DRAM_BASE is 0x8000_0000 by default.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/Kconfig | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 7895c77545f1..b4af1df86352 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -247,10 +247,16 @@ config MMU
>  	  Select if you want MMU-based virtualised addressing space
>  	  support by paged memory management. If unsure, say 'Y'.
>  
> +if !MMU
> +config DRAM_BASE
> +	hex '(S)DRAM Base Address'
> +	default 0x80000000
> +endif

I'm not sure but it feels odd to have this at top level config menu.
Maybe it would make more sense for this to be located under the
"Platform Type" section ?

Thanks,

Clément

> +
>  config PAGE_OFFSET
>  	hex
>  	default 0xC0000000 if 32BIT && MMU
> -	default 0x80000000 if !MMU
> +	default DRAM_BASE if !MMU
>  	default 0xff60000000000000 if 64BIT
>  
>  config KASAN_SHADOW_OFFSET