[U-Boot] [PATCH] ARM: tegra: CONFIG_{SYS_, }LOAD{_, }ADDR rationalization

[Paul Walmsley]

On 04/01/2015 03:40 PM, Stephen Warren wrote:
> From: Stephen Warren <swarren at nvidia.com>
>
> As best I can tell, CONFIG_SYS_LOAD_ADDR and CONFIG_LOADADDR/$loadaddr
> serve essentially the same purpose. Roughly, if a command takes a load
> address, then CONFIG_SYS_LOAD_ADDR or $loadaddr (or both) are the default
> if the command-line does not specify the address. Different U-Boot
> commands are inconsistent re: which of the two default values they use.
> As such, set the two to the same value, and move the logic that does this
>   into tegra-common-post.h so it's not duplicated. A number of other non-
> Tegra boards do this too.
>
> The values chosen for these macros are no longer consistent with anything
> in MEM_LAYOUT_ENV_SETTINGS. Regain consistency by setting $kernel_addr_r
> to CONFIG_LOADADDR. Older scripts tend to use $loadaddr for the default
> kernel load address, whereas newer scripts and features tend to use
> $kernel_addr_r, along with other variables for other purposes such as
> DTBs and initrds. Hence, it's logical they should share the same value.
>
> I had originally thought to make the $kernel_addr_r and CONFIG_LOADADDR
> have different values. This would guarantee no interference if a script
> used the two variables for different purposes. However, that scenario is
> unlikely given the semantic meaning associated with the two variables.
> The lowest available value is 0x90200000; see comments for
> MEM_LAYOUT_ENV_SETTINGS in tegra30-common-post.h for details. However,
> that value would be problematic for a script that loaded a raw zImage to
> $loadaddr, since it's more than 128MB beyond the start of SDRAM, which
> would interfere with the kernel's CONFIG_AUTO_ZRELADDR. So, let's not do
> that.
>
> The only potential fallout I could foresee from this patch is if someone
> has a script that loads the kernel to $loadaddr, but some other file
> (DTB, initrd) to a hard-coded address that the new value of $loadaddr
> interferes with. This seems unlikely. A user should not do that; they
> should either hard-code all load addresses, or use U-Boot-supplied
> variables for all load addresses. Equally, any fallout due to this change
> is trivial to fix; simply modify the load addresses in that script.
>
> Cc: Paul Walmsley <pwalmsley at nvidia.com>
> Signed-off-by: Stephen Warren <swarren at nvidia.com>
>

Reviewed-by: Paul Walmsley <pwalmsley at nvidia.com>

Thanks Stephen

- Paul

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