Re: [PATCH] Documentation: PCI: Document decoding of TLP Header in AER messages

Mika Westerberg
2026-03-23T11:03:04Z

On Mon, Mar 23, 2026 at 07:52:39AM +0100, Lukas Wunner wrote:
> The prefix/header of the TLP that caused an error is recorded by the Root
> Complex and emitted to the kernel log in raw hex format. Document the
> existence and usage of tlp-tool, which allows decoding the TLP Header
> into human-readable form.
>
> The TLP Header hints at the root cause of an error, yet is often ignored
> because of its seeming opaqueness. Instead, PCIe errors are frequently
> worked around by a change in the kernel without fully understanding the
> actual source of the problem. With more documentation on available tools
> we'll hopefully come up with better solutions.
>
> There are also wireshark dissectors for TLPs, but it seems they expect a
> complete TLP, not just the header, and they cannot grok the hex format
> emitted by the kernel directly. tlp-tool appears to be the most cut and
> dried solution out there.
>
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Maciej Grochowski <mx2pg@pm.me>

Good idea, this is useful.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>