linux-kernel - [PATCH -fixes] riscv: Do not restrict memory size because of linear mapping on nommu

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Message-Id: <20240827065230.145021-1-alexghiti@rivosinc.com>
Date: Tue, 27 Aug 2024 08:52:30 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	David McKay <david.mckay@...asip.com>,
	Stuart Menefy <stuart.menefy@...asip.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH -fixes] riscv: Do not restrict memory size because of linear mapping on nommu

It makes no sense to restrict physical memory size because of linear
mapping size constraints when there is no linear mapping, so only do
that when mmu is enabled.

Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Closes: https://lore.kernel.org/linux-riscv/CAMuHMdW0bnJt5GMRtOZGkTiM7GK4UaLJCDMF_Ouq++fnDKi3_A@mail.gmail.com/
Fixes: 3b6564427aea ("riscv: Fix linear mapping checks for non-contiguous memory regions")
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index eb0649a61b4c..1785782c2e55 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -252,7 +252,7 @@ static void __init setup_bootmem(void)
 	 * The size of the linear page mapping may restrict the amount of
 	 * usable RAM.
 	 */
-	if (IS_ENABLED(CONFIG_64BIT)) {
+	if (IS_ENABLED(CONFIG_64BIT) && IS_ENABLED(CONFIG_MMU)) {
 		max_mapped_addr = __pa(PAGE_OFFSET) + KERN_VIRT_SIZE;
 		memblock_cap_memory_range(phys_ram_base,
 					  max_mapped_addr - phys_ram_base);
-- 
2.39.2