Re: [PATCH v8 4/5] cxl/core, EINJ: Add CXL debugfs files and EINJ functions

[Ben Cheatham <benjamin.cheatham@amd.com>]

On 1/10/24 4:10 PM, Dan Williams wrote:
> Ben Cheatham wrote:
> [..]
>>>> +
>>>> +	dir = cxl_debugfs_create_dir(dev_name(dport->dport_dev));
>>>> +
>>>> +	debugfs_create_file("einj_inject", 0200, dir, dport,
>>>> +			    &cxl_einj_inject_fops);
>>>
>>> I will note that I am little bit uneasy about this ACPI'ism escaping
>>> into the common core, but he mitigation for me is that if some other
>>> platform firmware invented a platform-firmware method for error inject
>>> it would simply need to reuse the einj_cxl_ namespace to make it common.
>>>
>>
>> I'll be honest; I'm not sure I understand the concern here, but that's probably
>> just inexperience on my part. That being said, I don't mind changing it if you
>> have any suggestions!
>>
> 
> Notice how the CXL subsystem organizes all the ACPI interface concerns
> into drivers/cxl/acpi.c. There are some generic callbacks like the
> @calc_hb argument to cxl_root_decoder_alloc(), but there are no direct
> ties of the CXL core code to ACPI details. This separation allows, in
> principle, a non-ACPI platform (like PowerPC OpenFirmware) to support
> CXL without needing to unwind a bunch of CXL-ACPI specific stuff.
> 
> This "cxl_einj" work is leaking an ACPI specific term "EINJ" into the
> core code. The reason I am ok with this is that the ABI is still gated
> on CONFIG_ACPI_APEI_EINJ. Also, we still have the option to require that
> OpenFirmware error injection just call their user facing ABI "EINJ" as
> well, even if it is a different name in the OpenFirmware specification.
> To be clear though no one has sent patches for CXL support on anything
> other than ACPI based platforms.

Ok that makes sense, thanks for the explanation!