On 1 April 2015 at 15:40, Stephen Warren swarren@wwwdotorg.org wrote:
From: Stephen Warren swarren@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.
Reviewed-by: Simon Glass