[U-Boot] [PATCH] arm64: Keep macro PGTABLE_SIZE for non-full-va map

[york sun]

On 03/21/2016 12:29 PM, Alexander Graf wrote:
> 
> On Mar 21, 2016, at 8:23 PM, york sun <york.sun at nxp.com> wrote:
> 
>> On 03/21/2016 12:12 PM, Alexander Graf wrote:
>>>
>>> On Mar 21, 2016, at 7:59 PM, York Sun <york.sun at nxp.com> wrote:
>>>
>>>> Commit 7985cdf removed non-full-va map code, replaced PGTABLE_SIZE
>>>> with get_page_table_size() function for all. It is incorrect for
>>>> platforms with non-full-va mapping, at this moment Layerscape SoCs.
>>>>
>>>> Signed-off-by: York Sun <york.sun at nxp.com>
>>>> CC: Alexander Graf <agraf at suse.de>
>>>> CC: Alison Wang <alison.wang at nxp.com>
>>>> CC: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>
>>>> ---
>>>> arch/arm/include/asm/system.h |    4 ++++
>>>> 1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
>>>> index ac1173d..fab6f0c 100644
>>>> --- a/arch/arm/include/asm/system.h
>>>> +++ b/arch/arm/include/asm/system.h
>>>> @@ -20,7 +20,11 @@
>>>> #ifndef __ASSEMBLY__
>>>>
>>>> u64 get_page_table_size(void);
>>>> +#ifdef CONFIG_SYS_FULL_VA
>>>
>>> This macro doesn't exist anymore. We need to do something different. Let me cook up a patch.
>>>
>>
>> Thanks.
>>
>> After this, I want to discuss the possibility to use the new infrastructure for
>> our SoCs. The key is we have limited on-chip RAM before DDR is initialized. We
>> cannot use full va mapping for this reason for early MMU tables. We should have
> 
> I'm not sure I understand this part. How is full va different from your current approach? The only really major difference is that you can do non-1:1 maps.
> 
> If all maps are aligned, you shouldn't waste too much memory compared to your current approach, no?
> 
The new full va map doesn't map all space, only the selected mapping in the
table, correct? If yes, we should be able to fix the tables in the on-chip RAM.

I think my case is different because I use two tables. The final table is
equivalent to those everyone else is using. The early table is different with
non 1:1 mapping. This feature shouldn't be too hard to add.

Now it comes the third part. The early table is so early, we don't have gd setup
yet, or printf. We need to change the table handling to accept an argument,
instead of using gd for table pointer.

York