[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 12:27 PM
> To: Tom Warren
> Cc: u-boot at lists.denx.de; Simon Glass; Stephen Warren; Thierry Reding;
> Marcel Ziswiler
> Subject: Re: [U-Boot] [PATCH] ARM: tegra: restrict usable RAM size further
> 
> 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.
Ah, yes. Missed that.

--
nvpublic