On 29.08.18 22:52, Heinrich Schuchardt wrote:
On 08/29/2018 08:53 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
Tegra U-Boot ensures that board_get_usable_ram_top() never returns a value over 4GB, since some peripherals can't access such addresses. However, on systems with more than 2GB of RAM, RAM bank 1 does describe this extra RAM, so that Linux (or whatever OS) can use it, subject to DMA limitations. Since board_get_usable_ram_top() points at the top of RAM bank 0, the memory locations describes by RAM bank 1 are not mapped by U-Boot's MMU configuration, and so cannot be used for anything.
For some completely inexplicable reason, U-Boot's EFI support ignores the value returned by board_get_usable_ram_top(), and EFI memory allocation routines will return values above U-Boot's RAM top. This causes U-Boot to crash when it accesses that RAM, since it isn't mapped by the MMU. One use-case where this happens is TFTP download of a file on Jetson TX1 (p2371-2180).
This change explicitly tells the EFI code that this extra RAM should not be used, thus avoiding the crash.
A previous attempt to make EFI honor board_get_usable_ram_top() was rejected. So, this patch will need to be replicated for any board that implements board_get_usable_ram_top().
Fixes: aa909462d018 ("efi_loader: efi_allocate_pages is too restrictive") Signed-off-by: Stephen Warren swarren@nvidia.com
arch/arm/mach-tegra/board2.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/arch/arm/mach-tegra/board2.c b/arch/arm/mach-tegra/board2.c index 421a71b3014d..869d5d99d2fd 100644 --- a/arch/arm/mach-tegra/board2.c +++ b/arch/arm/mach-tegra/board2.c @@ -6,6 +6,7 @@
#include <common.h> #include <dm.h> +#include <efi_loader.h> #include <errno.h> #include <ns16550.h> #include <usb.h> @@ -210,6 +211,19 @@ int board_early_init_f(void)
int board_late_init(void) { +#ifdef CONFIG_EFI_LOADER
- if (gd->bd->bi_dram[1].start) {
/** Only bank 0 is below board_get_usable_ram_top(), so all of* bank 1 is not mapped by the U-Boot MMU configuration, and so* we must prevent EFI from using it.*/efi_add_memory_map(gd->bd->bi_dram[1].start,gd->bd->bi_dram[1].size / 4096,Please, do not hard code the page size here. You can use
EFI_PAGE_SHIFT. The constant is defined in efi.h.
EFI_RESERVED_MEMORY_TYPE, false);The EFI spec says:
"Regions that are backed by physical hardware, but are not supposed to be accessed by the OS, must be returned as EfiReservedMemoryType."
I assume this is not what you want. To only avoid that the U-Boot EFI implementation uses the memory make it EFI_BOOT_SERVICES_DATA.
Basically it boils down to what the memory is reserved for. For DRAM that the OS should use, use EFI_BOOT_SERVICES_DATA. That way no U-Boot allocations will use the memory, but Linux for example will.
If the memory however should not be used by an OS either (like a reserved ATF region), then mark it as reserved.
Alex