[PATCH 1/5] riscv: nommu: remove PAGE_OFFSET hardcoding

From: Jisheng Zhang <jszhang@kernel.org>
To: 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>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/5] riscv: nommu: remove PAGE_OFFSET hardcoding
Date: Tue, 26 Mar 2024 00:40:17 +0800	[thread overview]
Message-ID: <20240325164021.3229-2-jszhang@kernel.org> (raw)
In-Reply-To: <20240325164021.3229-1-jszhang@kernel.org>

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
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..afd51dbdc253 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
+
 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
-- 
2.43.0


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