On 31.03.18 16:13, Mark Kettenis wrote:
Currently U-Boot doesn't make any effort to reserve the memory used by ARM Trusted Firmware on these platforms. The result is that the memory is listed as available in the EFI memory map. And as soon as a loaded kernel tries to use this memory things explode. I've seen this with the OpenBSD kernel. But I totally expect a Linux kernel to suffer the same fate.
Please make sure to CC people you think would be interested. In this case, I believe Stefan certainly would care. Me too :).
I'm currently using the diff below, but it is not entirely clear to me if arch_early_init_r() is the appropriate place to do this. I'm also wondering whether the block should also be marked as reserved in the FDT using fdt_add_mem_rsv(). If the latter is required this probably needs to be done by ft_board_setup() or ft_system_setup().
The address and size of the region have been taken from Marvell's ATF fork at
https://github.com/MarvellEmbeddedProcessors/atf-marvell
The memory layout is defined in
plat/marvell/a8k/common/include/platform_def.h
where there are lots of defines and a diagram that attempt to describe the memory. It is not entirely obvious to me what part needs to be reserved. But 0x0400000-0x04200000 works.
Yeah, so ATF resides in RAM and U-Boot obviously needs to propagate that information.
I actually think for mvebu it might make sense to completely override efi_add_known_memory(). If I read all the bdinfo logic correctly, they're going through great lengths to reduce the amount of address space they propagate in bi_dram:
https://github.com/u-boot/u-boot/blob/master/arch/arm/mach-mvebu/dram.c#L274
That of course means our memory map is completely bogus. So instead, what I would do is create an override for efi_add_known_memory() where you just walk the dram slots yourself and add all memory you find as BOOTTIME_DATA. That way the OS will know that it can use it for itself, but it won't be used during boot time.
Then, go through bi_dram and force all those regions as free memory.
And at last, reserve the ATF range as reserved. And yes, you want to do that in both - EFI map and as FDT fixup.
Alex