Explain with an example configuring of Inbound and Outbound addresses in PCIe (Address Translation)

[TRINATH KARRI]

Explain with an example configuring of Inbound and Outbound addresses in PCIe (Address Translation)

 

[TuxBot]

Explain with an example configuring of Inbound and Outbound addresses in PCIe (Address Translation)

Dude, configuring Inbound and Outbound addresses in PCIe (Address Translation) is all about mapping the addresses between the host and the device. Let me break it down for you with an example.

Let's say we have a PCIe device with a bunch of registers, and we want to access these registers from the host. The device has its own address space, and we need to map it to the host's address space.

Inbound addresses refer to the addresses used by the PCIe device. These addresses are typically called the device's "BARs" (Base Address Registers). Each BAR corresponds to a range of addresses in the device's address space. The device uses these addresses to communicate with the host.

On the other hand, Outbound addresses refer to the addresses used by the host. These addresses are the ones that the host uses to access the device's registers. The host needs to translate these addresses to the device's address space so that it can communicate with the device.

To configure the Inbound and Outbound addresses, you'll need to set up the PCIe Address Translation Unit (ATU) or the Memory Management Unit (MMU) in the PCIe bridge or switch. These units handle the address translation between the host and the device.

Here's an example configuration using the Linux kernel's pci_alloc_resource_start() and pci_alloc_resource_end() functions:

pci_resource_t bar;  // represents the device's BAR
resource_size_t inbound_address;  // address in the device's address space
resource_size_t outbound_address;  // address in the host's address space

// Assuming you have already retrieved the device BAR
bar = pci_resource_start(pdev, bar_index);

// Set the inbound address
inbound_address = bar;

// Set the outbound address
outbound_address = pci_resource_start(pdev, bar_index);

// Now you can communicate with the device using these addresses

That's the basic idea, bro. You map the device's BAR to the inbound address, and you map the outbound address to the host's address. That way, the host can access the device's registers as if they were part of its own address space.

Remember, this is just a superficial overview, dude. If you want more specific details or code examples, let me know!

 

[TRINATH KARRI]

@TuxBot Can you explain with a proper example address write taking RC and EP