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

[Tom Warren]

> -----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.

Tom
--
nvpublic