On 11/16/2015 09:21 AM, Joakim Tjernlund wrote: > On Mon, 2015-11-16 at 09:03 -0800, York Sun wrote: >> >> On 11/12/2015 02:54 PM, Joakim Tjernlund wrote: >>> On Thu, 2015-11-12 at 14:20 -0800, York Sun wrote: >>>> Introduce a new function to calculate reserved memory to replace macro >>>> CONFIG_SYS_MEM_TOP_HIDE for more flexibility. Legacy use of this macro is >>>> still supported. MC and debug server are not board-specific. Move the >>>> reservation function to SoC file. Reduce debug server memory by 2MB to >>>> make room for secure memory. >>> >>> I would make sure "pram" is first to reserve memory, is it? >>> >> >> (previous reply wasn't caught by patchwork, adding more info) >> >> Yes, pram is used to reserve small memory from the top of u-boot memory, not >> necessarily the top of total memory. For example, a 32-bit u-boot with large >> memory. This patch deals with carving memory from the end of memory, which >> could >> be far away from u-boot top. Even in system with small memory, it is still >> correct, because pram reserves memory from the _top_ of u-boot and this >> mechanism reserved memory is hidden from u-boot. > > And I realize I am mixing pram and CONFIG_SYS_MEM_TOP_HIDE. Your patch > reserves memory before CONFIG_SYS_MEM_TOP_HIDE which might be confusing > for some. Why do you need another( then CONFIG_SYS_MEM_TOP_HIDE) method to > reserve memory? >
I am not going to discover the legacy reason to have CONFIG_SYS_MEM_TOP_HIDE. For my current use on ARMv8, we have management complex (aks MC) and debug server. They both require a big chunk of private memory (even after OS boots up). I am taking advantage of existing CONFIG_SYS_MEM_TOP_HIDE to reserve this memory without fragment memory and without the need to create reserved memory node in device tree. With that in place, I think it makes sense to do the same way for reserving secure memory. York _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
