Hello all, I was reading https://elinux.org/Device_Tree_Usage#Ranges_.28Address_Translation.29 and have a question (I have read it in the past). In the device tree node for the PCI bridge, there is "ranges" property and this is to show the address mapping between PCI address and CPU physical address. And this seems to be the relationship between BARs and the CPU physical address and this is usually determined and set by the firmware before linux boots by filling in the BARs and setting the PCI bridge's address translation logic appropriately. So does this mean this pci node in the device tree is filled (or modified) by the firmware(BIOS) during initialization and passed to the OS? (I guess so). I know how the BIOS or firmware detects the address ranges's type (memory or IO, cachable, and size) from the initial BAR registers and fills them. I'd appreciate it if someone could confirm this. (and the dma-ranges property seems to be the relationship between PCI address and the host side memory address) Thank you! Chan Kim _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
