On Mon, Apr 25, 2016 at 10:13 AM, Aaron Durbin adurbin@google.com wrote:
On Fri, Apr 22, 2016 at 9:35 PM, Stefan Reinauer stefan.reinauer@coreboot.org wrote:
On 04/22/2016 02:35 PM, Aaron Durbin via coreboot wrote:
- coreboot tables base address and size.
- console base address and size.
- ramoops info.
Since ramoops already has its own object in the DSDT, do we want to mention it here? What about other cbmem entries? coverage, timestamps...? Do we want a pointer to cbmem in there, instead?
All of those things are in the coreboot table already. We can use the same code/parser for ARM (and other device tree archs) as x86. The only difference is where to source the initial information for where the table resides.
Here's the 1 million dollar question: Do we want to get rid of coreboot table and only have a coreboot specific table? For a non-ACPI OS it's not much harder to read a (non-DSDT) ACPI table than the current coreboot table approach. For ACPI OSes it might make things a bit easier (and counter the argument that coreboot requires "support for non-standard tables")
On Fri, Apr 22, 2016 at 2:00 PM, Duncan Laurie dlaurie@chromium.org wrote:
On Tue, Apr 19, 2016 at 6:49 AM, Aaron Durbin adurbin@google.com wrote:
On Mon, Apr 18, 2016 at 10:17 PM, Julius Werner jwerner@chromium.org wrote:
I think we should only export the coreboot table location and size through ACPI and then read everything else from there. That way we can share almost all of the kernel driver code with ARM and just need a tiny platform-specific stub to look up the table location first. If we add all the information into an actual ACPI table, we're building an x86-only solution again. (A generic, platform-independent coreboot driver could just as easily export the stuff we want into sysfs.)
That's fine. The only thing I was concerned about was implementing an ACPI table proper or try to do some ACPI device shenanigans like the ramoops device. coreboot doesn't currently have a ACPI ID assigned to it. If we go with a ACPI device coreboot should apply for an ACPI ID. I personally think the coreboot ACPI table seems more straight forward, but I was wondering if people knew of any downsides to going that route.
The official tables are all defined in the ACPI spec while the related tables are also linked to from the spec, so we'd need to convince the UEFI forum to at least reserve the signature for us (and then link to our table definition) since they intend to act as gatekeepers to avoid collisions in table signatures:
I like the idea of having a separate table rather than an object.
We can pursue that if it's needed, but it sounds like it should be easy to just apply for HID and place a coreboot device object in the acpi code.
"Requests to reserve a 4-byte alphanumeric table signature should be sent to the email address info@acpi.info and should include the purpose of the table and reference URL to a document that describes the table format."
An easier path would be to define a specific device in the DSDT and populate it with the various data we want to be there on every system. That would allow us to control the format and be able to alter it in the future if we want to expose new information.
As you note a Device would need a valid unique HID, and that needs an ID prefix if it wants to be official. In theory we could request something like "CORE" as an official APCI ID from http://www.uefi.org/PNP_ACPI_Registry
OK. Time for bikeshedding:
- CORE
This one is it!
Did CORE get requested from the ACPI forum as a hid we can use? I think it should be fairly easy to request and get.
-Aaron