[S] Change in coreboot[main]: mainboard/qemu-riscv: Get top of memory from device-tree blob

[Alper Nebi Yasak (Code Review)]

Attention is currently required from: Maximilian Brune, Nico Huber, Philipp Hug, Ron Minnich.

Hello Philipp Hug, Ron Minnich, build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/80363?usp=email

to look at the new patch set (#5).

The following approvals got outdated and were removed:
Verified+1 by build bot (Jenkins)

Change subject: mainboard/qemu-riscv: Get top of memory from device-tree blob
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mainboard/qemu-riscv: Get top of memory from device-tree blob

Trying to probe RAM space to figure out top of memory causes an
exception on RISC-V virtual machines with recent versions of QEMU, but
we temporarily enable exception handlers for that and use it to help
detect if a RAM address is usable or not. However, QEMU docs recommend
reading device information from the device-tree blob it provides us at
the start of RAM.

A previous commit adds a library function to parse device-tree blob that
QEMU provides us. Use it to determine top of memory in RISC-V QEMU
virtual machines, but still fall back to the RAM probing approach as a
last-ditch effort.

Change-Id: I9e4a95f49ad373675939329eef40d7423a4132ab
Signed-off-by: Alper Nebi Yasak 
---
M src/mainboard/emulation/qemu-riscv/Kconfig
M src/mainboard/emulation/qemu-riscv/cbmem.c
2 files changed, 9 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/63/80363/5