Boot from 64-bit memory address?

[Bernard, Philip]

Hi,

Is it possible to boot from a DRAM memory address beyond the 32-bit boundary? I'm trying to configure a new RISC-V board which has 2GB of DRAM starting at offset 0x40_0000_0000. I started from the settings for an existing RISC-V board and made adjustments for my HW, but when I try to boot, I run into an "out of memory" error.

>From https://u-boot.readthedocs.io/en/latest/develop/uefi/u-boot_on_efi.html#tables I noticed that U-Boot will only use "conventional" memory which is 4GB and below, so it seems like this may not be possible? Looking through the repo, I also noticed that nearly every device is configuring settings like CONFIG_SYS_LOAD_ADDR with a 32-bit value, so I haven't found any examples to emulate for my use case.

I'm hoping someone knows the mistake I'm making or can confirm that this isn't possible. Appreciate the help.

Best,
Phil


Below is the output from U-Boot:

U-Boot SPL 2022.07 (Feb 23 2023 - 00:50:44 +0000)
Trying to boot from RAM

OpenSBI v1.1
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
| |  | |_ __   ___ _ __ | (___ | |_) || |
| |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
| |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name             : test,test
Platform Features         : medeleg
Platform HART Count       : 1
Platform IPI Device       : aclint-mswi
Platform Timer Device     : aclint-mtimer @ 1000000Hz
Platform Console Device   : uart8250
Platform HSM Device       : ---
Platform Reboot Device    : ---
Platform Shutdown Device  : ---
Firmware Base             : 0x80000000
Firmware Size             : 276 KB
Runtime SBI Version       : 1.0

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*
Domain0 Region00          : 0x0000000002000000-0x000000000200ffff (I)
Domain0 Region01          : 0x0000000080000000-0x000000008007ffff ()
Domain0 Region02          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address      : 0x0000004001200000
Domain0 Next Arg1         : 0x0000004001267830
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART Priv Version    : v1.10
Boot HART Base ISA        : rv64imafdcb
Boot HART ISA Extensions  : time
Boot HART PMP Count       : 8
Boot HART PMP Granularity : 4
Boot HART PMP Address Bits: 54
Boot HART MHPM Count      : 0
Boot HART MIDELEG         : 0x0000000000000222
Boot HART MEDELEG         : 0x000000000000b109


U-Boot 2022.07 (Feb 23 2023 - 00:50:44 +0000)

CPU:   rv64imafdc
Model: test,test
DRAM:  2 GiB
Core:  11 devices, 8 uclasses, devicetree: separate
ERROR: Out of memory
Loading Environment from nowhere... OK
In:    serial at 131400000
Out:   serial at 131400000
Err:   serial at 131400000
Model: test,test
Net:   No ethernet found.
Hit any key to stop autoboot:  0
Moving Image from 0x4006000000 to 0x4000200000, end=4000b01c8c
## Flattened Device Tree blob at ff76a1d0
   Booting using the fdt blob at 0xff76a1d0
ERROR: Failed to allocate 0x1000000 bytes below 0x100000000.
ramdisk - allocation error