Re: Porting barebox to Novena: misc questions

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Mar 18, 2014 at 04:43:32PM +0800, Sean Cross wrote:
> > arm_add_mem_device("ram0", 0x10000000, SZ_2G + SZ_1G + SZ_512M + SZ_128M + SZ_1M);
> > 
> > and this works on a board I have here (although that board doesn't even
> > have that amount of memory)
> 
> Oh, I didn't realize there was a requirement to align to the nearest
> megabyte.
> 
> In that case, you're right.  I tried this, and it works:
> 
> arm_add_mem_device("ram0", 0x10000000, SZ_2G + SZ_1G + SZ_512M + SZ_256M
> - SZ_1M);
> 
> However, this fails:
> 
> arm_add_mem_device("ram0", 0x10000000, SZ_2G + SZ_1G + SZ_512M + SZ_256M);

You are really exploring corner cases here ;)

Try this:

--------------------------8<--------------------

From 4a84905c61d4a4a895c83f4f156f60a7258e6413 Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Tue, 18 Mar 2014 09:53:18 +0100
Subject: [PATCH] ARM: MMU: Fix memory reaching to the end of address space

For memory reaching the end of the address space
phys + bank->size overflows to 0. Fix this by right shifting
phys and bank->size before adding them.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/arm/cpu/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
index 84daa3d..bf0141b 100644
--- a/arch/arm/cpu/mmu.c
+++ b/arch/arm/cpu/mmu.c
@@ -200,7 +200,7 @@ static int arm_mmu_remap_sdram(struct memory_bank *bank)
 {
 	unsigned long phys = (unsigned long)bank->start;
 	unsigned long ttb_start = phys >> 20;
-	unsigned long ttb_end = (phys + bank->size) >> 20;
+	unsigned long ttb_end = (phys >> 20) + (bank->size >> 20);
 	unsigned long num_ptes = bank->size >> 10;
 	int i, pte;
 	u32 *ptes;
-- 
1.9.0

-- 
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