On 08/11/2022 08:18, Shao Miller wrote:
Good day, everyone.
Hi!
I seem to be fumbling around and unable to identify the correct manner
for informing the kernel that particular identity-mapped
memory-regions are special-purpose and ought not to be considered
"free" nor "available." I have tried 2 methods (and both together):
1. Manually adding them into arm_build_translation_table in
sys/arch/arm/arm/armv6_start.S
2. Returning the entries via the DEVMAP_ENTRY macros as a struct
pmap_devmap in my platform's .ap_devmap
Do you need to access these special memory regions during early boot
because both method above are aimed at this use case.
The memory regions are normally described in the FDT
/memory@80000000
device_type = "memory"
reg = <0 0x80000000 0x1 0>
with optional /reserved-memory areas
/reserved-memory
#address-cells = <0x2>
#size-cells = <0x2>
ranges
/reserved-memory/mmode_resv0@80000000
reg = <0 0x80000000 0 0x80000>
Perhaps you're missing the latter?
Nick