[U-Boot] [PATCH 4/9] tegra: Replace home grown mmu code with generic table approach

[Michal Simek <michal.simek@xilinx.com>]

On 22.2.2016 19:28, Stephen Warren wrote:
> On 02/21/2016 06:57 PM, Alexander Graf wrote:
>> Now that we have nice table driven page table creating code that gives
>> us everything we need, move to that.
> 
>> diff --git a/include/configs/tegra210-common.h
>> b/include/configs/tegra210-common.h
> 
>> +#define CONFIG_SYS_FULL_VA
>> +#define CONFIG_SYS_MEM_MAP {                        \
>> +    {                                \
>> +        .base = 0x0UL,                        \
>> +        .size = 0x80000000UL,                    \
>> +        .attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |        \
>> +             PTE_BLOCK_NON_SHARE |                \
>> +             PTE_BLOCK_PXN | PTE_BLOCK_UXN            \
>> +    }, {                                \
>> +        .base = 0x80000000UL,                    \
>> +        .size = 0xff80000000UL,                    \
>> +        .attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |            \
>> +             PTE_BLOCK_INNER_SHARE                \
>> +    },                                \
>> +    }
> 
> I'd prefer a layout that didn't align the closing } for different
> nesting levels in the same column. To avoid indenting everything a lot,
> it seems simplest to pull the final } back into the first column.
> 
> I believe the .size field of the second entry in the array only needs to
> be 0x80000000. Testing with a PCIe Ethernet card on p2371-2180 (the
> driver for which sets up noncached entries in the page tables, hence
> should exercise all this code) confirms that.
> 
> While recent Tegra systems do support more than 2GB of RAM, U-Boot will
> itself only use the first 2GB, so that PAs over 4GB are not used. See
> board_get_usable_ram_top() in arch/arm/mach-tegra/board2.c. That's
> because some peripherals can only access 32-bit PAs, and the simplest
> way to accommodate that is to ignore any RAM above the 32-bit limit.

Didn't you use mtest to test memory above of 2GB?

Thanks,
Michal