I'll like to reserved the first 2 GB to the RAM because my hardware write in this position to the memory RAM and I need to the kernel don't touch this part to the memory.
I read to use this option need launch the order memmap in the bootloader and the bootloader to I use is U-Boot because I'm dessing to Driver-Kernel in Yocto OS.
I read this to example to use the memmap:
memmap=nn[KMG]$ss[KMG] [KNL,ACPI] Mark specific memory as reserved. Region of memory to be reserved is from ss to ss+nn. Example: Exclude memory from 0x18690000-0x1869ffff memmap=64K$0x18690000 or memmap=0x10000$0x18690000 Some bootloaders may need an escape character before '$', like Grub2, otherwise '$' and the following number will be eaten.
And I don't know to use in this case, thankyou
EDIT: New question
I write this option in the U-Boot, using memmap=2G$0x00000000 and memmap=7fffffff$0x00000000, don't return exception, I guess I write this correctly but in cat / proc / iomem I do not see anything that tells me this memory is reserved for memory.
Would you need to modify .dtb?