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From: Borislav Petkov <bp@alien8.de>
To: Yazen Ghannam <yazen.ghannam@amd.com>
Cc: linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org,
	tony.luck@intel.com, x86@kernel.org,
	Smita.KoralahalliChannabasappa@amd.com
Subject: Re: [PATCH v2 8/8] x86/MCE/AMD Support new memory interleaving modes during address translation
Date: Mon, 28 Sep 2020 20:14:07 +0200	[thread overview]
Message-ID: <20200928181407.GH1685@zn.tnic> (raw)
In-Reply-To: <20200928155350.GA926956@yaz-nikka.amd.com>

On Mon, Sep 28, 2020 at 10:53:50AM -0500, Yazen Ghannam wrote:
> I don't have any clear reasons. I just get vague use cases sometimes
> about not using EDAC and relying on other things. But it shouldn't hurt
> to have the module load anyway. The EDAC messages can be suppressed, and
> the sysfs interface can be ignored. So, after a bit more thought, this
> doesn't seem like a good reason.

Ok. We can always carve it out if someone comes up with a valid reason
later.

> I agree that the translation code is implementation-specific and applies
> only to DRAM ECC errors, so it make sense to have it in amd64_edac. The
> only issue is getting the address translation to earlier notifiers. I
> think we can add a new one in amd64_edac to run before others. Maybe this
> can be a new priority class like MCE_PRIO_PREPROCESS, or something like
> that for notifiers that fixup the MCE data.

Well, I'm not sure you need notifiers here - you wanna call
mce_usable_address() and in it, it should do the address conversion
calculation to give you a physical address which you can feed to
memory_failure etc.

Now, mce_usable_address() is core code and we can make core code call
into a module but that is yucky. So *that* is your reason for keeping it
where it is.

Looking at its size:

$ readelf -s vmlinux | grep umc_normaddr_to
  2864: ffffffff817d8ae5   168 FUNC    LOCAL  DEFAULT    1 umc_normaddr_to_[...]
 91866: ffffffff81030e00  1127 FUNC    GLOBAL DEFAULT    1 umc_normaddr_to_[...]

that's something like ~1.3K and if you split it and do some
experimenting, you might get it even slimmer. Not that ~1.3K is that
huge for current standards but we should always aim at not bloating the
fat guy our kernel already is.

Thx.

-- 
Regards/Gruss,
    Boris.

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

  reply	other threads:[~2020-09-28 18:14 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-03 20:01 [PATCH v2 0/8] AMD MCA Address Translation Updates Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 1/8] x86/CPU/AMD: Save NodeId on AMD-based systems Yazen Ghannam
2020-09-09 18:06   ` Borislav Petkov
2020-09-09 20:17     ` Yazen Ghannam
2020-09-10 10:14       ` Borislav Petkov
2020-09-14 19:20         ` Yazen Ghannam
2020-09-15  8:35           ` Borislav Petkov
2020-09-16 19:51             ` Yazen Ghannam
2020-09-17 10:37               ` Borislav Petkov
2020-09-17 16:20                 ` Yazen Ghannam
2020-09-17 16:40                   ` Borislav Petkov
2020-09-17 19:44                     ` Yazen Ghannam
2020-09-17 20:10                       ` Borislav Petkov
2020-09-03 20:01 ` [PATCH v2 2/8] x86/CPU/AMD: Remove amd_get_nb_id() Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 3/8] EDAC/mce_amd: Use struct cpuinfo_x86.node_id for NodeId Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 4/8] x86/MCE/AMD: Use defines for register addresses in translation code Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 5/8] x86/MCE/AMD: Use macros to get bitfields " Yazen Ghannam
2020-09-21 13:58   ` Borislav Petkov
2020-09-03 20:01 ` [PATCH v2 6/8] x86/MCE/AMD: Drop tmp variable " Yazen Ghannam
2020-09-23  8:05   ` Borislav Petkov
2020-09-23 16:05     ` Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 7/8] x86/MCE/AMD: Group register reads " Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 8/8] x86/MCE/AMD Support new memory interleaving modes during address translation Yazen Ghannam
2020-09-23  8:20   ` Borislav Petkov
2020-09-23 16:25     ` Yazen Ghannam
2020-09-25  7:22       ` Borislav Petkov
2020-09-25 19:51         ` Yazen Ghannam
2020-09-28  9:47           ` Borislav Petkov
2020-09-28 15:53             ` Yazen Ghannam
2020-09-28 18:14               ` Borislav Petkov [this message]
2020-09-29 13:21                 ` Yazen Ghannam

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