[U-Boot] [PATCH] ARM: tegra: restrict usable RAM size further

[Stephen Warren]

On 08/05/2015 01:22 PM, Tom Warren wrote:
>> -----Original Message-----
>> From: Stephen Warren [mailto:swarren at wwwdotorg.org]
>> Sent: Wednesday, August 05, 2015 11:33 AM
>> To: Tom Warren
>> Cc: u-boot at lists.denx.de; Simon Glass; Stephen Warren; Thierry Reding
>> Subject: Re: [U-Boot] [PATCH] ARM: tegra: restrict usable RAM size further
>>
>> On 07/29/2015 01:47 PM, Stephen Warren wrote:
>>> From: Stephen Warren <swarren at nvidia.com>
>>>
>>> Additionally, ARM64 devices typically run a secure monitor in EL3 and
>>> U-Boot in EL2, and set up some secure RAM carve-outs to contain the
>>> EL3 code and data. These carve-outs are located at the top of 32-bit
>>> address space. Restrict U-Boot's RAM usage to well below the location
>>> of those carve-outs. Ideally, we would the secure monitor would inform
>>> U-Boot of exactly which RAM it could use at run-time. However, I'm not
>>> sure how to do that at present (and even if such a mechanism does
>>> exist, it would likely not be generic across all forms of secure monitor).
>>
>> TomW, what are your thoughts on applying this given the discussion thread?
>> Thanks.
 >
> I think this patch is fine. I have not set up any TZ/other carveouts (NVDEC,VPR,GPU,TSEC, etc.) yet in U-Boot, but I have in coreboot, and right now we're using approx. 153MB (0xf66c0000 - 0x100000000).  So 512MB here seems large but OK, given that we'll still have tons of SDRAM left on most any modern board.
>
> I can take this in on the next pass, if no one objects. Adding Marcel for Colibri T20/T30, since this'll affect those boards, too.

Thanks. This should only affect Tegra210 boards, since the function I 
modified is under #ifdef CONFIG_ARM64.