linux-kernel - Re: [PATCH 1/3] x86/MCE/AMD: Provide an "Unknown" MCA bank type

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Date:   Sat, 11 Dec 2021 16:39:01 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com, mukul.joshi@....com,
        alexander.deucher@....com, william.roche@...cle.com
Subject: Re: [PATCH 1/3] x86/MCE/AMD: Provide an "Unknown" MCA bank type

On Tue, Dec 07, 2021 at 04:28:42PM +0000, Yazen Ghannam wrote:
> Sure thing. But I don't think removing the second directory will be okay. The
> layout is "bank"/"block". If the "block" has special use like DRAM ECC, or L3
> Cache on older systems, then it'll have a unique name. Otherwise, the block
> will take the name of the bank.

Ah, there was something... and I found a good example on my zen1 box:

├── umc_0
│   ├── dram_ecc
│   │   ├── error_count
│   │   ├── interrupt_enable
│   │   └── threshold_limit
│   └── misc_umc
│       ├── error_count
│       ├── interrupt_enable
│       └── threshold_limit

but yeah, that still doesn't make it clear how the hierarchy is...

> /sys/devices/system/machinecheck/machinecheck0/thresholding
> ├── bank0
> │   ├── desc ("Instruction Fetch")
> │   └── block0
> │       ├── desc ("All Errors")
> │       ├── error_count
> │       ├── interrupt_enable
> │       └── threshold_limit
> ├── bank1
> │   ├── desc ("Northbridge")
> │   ├── block0
> │   │   ├── desc ("DRAM Errors")
> │   │   ├── error_count
> │   │   ├── interrupt_enable
> │   │   └── threshold_limit
> │   └── block1
> │       ├── desc ("Link Errors")
> │       ├── error_count
> │       ├── interrupt_enable
> │       └── threshold_limit
> ...
> 
> I'm inclined to the second option, since it keeps all the thresholding
> functionality under a single directory.

Yeah, that makes it explicit and one can see that a bank can have
multiple blocks.

Renaming will change the ABI but we can always do symlinks later if
people complain. Which I doubt because I've yet to hear of someone using
that thresholding thing at all...

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette