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From: Borislav Petkov <bp@alien8.de>
To: Robert Richter <rrichter@marvell.com>
Cc: James Morse <james.morse@arm.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	"linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 02/24] EDAC, ghes: Fix grain calculation
Date: Mon, 12 Aug 2019 14:38:47 +0200
Message-ID: <20190812123847.GC23772@zn.tnic> (raw)
In-Reply-To: <20190812120517.2kktugib244ujgvb@rric.localdomain>

On Mon, Aug 12, 2019 at 12:05:25PM +0000, Robert Richter wrote:
> So for masks in the range from 0xffffffffff000000 to
> 0xffffffffff7fffff we have grain_bits set to 24, which corresponds to
> a grain of 0x1000000.

I don't think you're reading what I'm trying to say so let me go into
more detail:

I'm very suspicious about any and all information we get from firmware.
I think that is clear why by now.

If we get an address mask, we better sanity-check that mask. For
example, whether it is contiguous or whether the set bits in it are even
making any sense and so on.

What you're doing is assuming the firmware will give you a sensible mask
and you start working with it without checking it.

For example, if you get a mask of 0xffffffffff00ff00, how do you know
that the grain bits are really 24? Says who? There's a hole in the damn
mask so it could just as well be *anything* *but* an address mask. Hell,
it can be some random garbage.

Do you catch my drift now?

But, since we don't use the grain all too much and don't depend on it
yet, we keep it simple and lazy for now:

> > "I guess we can leave it like that for now until some "inventive"
> > firmware actually does it."

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24 15:08 [PATCH v2 00/24] EDAC, mc, ghes: Fixes and updates to improve memory error reporting Robert Richter
2019-06-24 15:08 ` [PATCH v2 01/24] EDAC, mc: Fix grain_bits calculation Robert Richter
2019-08-03 10:08   ` Borislav Petkov
2019-06-24 15:08 ` [PATCH v2 02/24] EDAC, ghes: Fix grain calculation Robert Richter
2019-08-09 13:15   ` Borislav Petkov
2019-08-12  6:42     ` Robert Richter
2019-08-12  7:32       ` Borislav Petkov
2019-08-12 12:05         ` Robert Richter
2019-08-12 12:38           ` Borislav Petkov [this message]
2019-06-24 15:08 ` [PATCH v2 03/24] EDAC, ghes: Remove pvt->detail_location string Robert Richter
2019-08-02 17:04   ` James Morse
2019-08-07  9:00     ` Robert Richter
2019-08-13  8:09   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 04/24] EDAC, ghes: Unify trace_mc_event() code with edac_mc driver Robert Richter
2019-06-24 15:09 ` [PATCH v2 05/24] EDAC, mc: Fix and improve sysfs init functions Robert Richter
2019-08-13  8:26   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 06/24] EDAC: Kill EDAC_DIMM_PTR() macro Robert Richter
2019-08-13 14:59   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 07/24] EDAC: Kill EDAC_DIMM_OFF() macro Robert Richter
2019-08-14 14:52   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 08/24] EDAC: Introduce mci_for_each_dimm() iterator Robert Richter
2019-08-14 15:18   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 09/24] EDAC, mc: Cleanup _edac_mc_free() code Robert Richter
2019-08-14 16:31   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 10/24] EDAC, mc: Remove per layer counters Robert Richter
2019-08-16  9:24   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 11/24] EDAC, mc: Rework edac_raw_mc_handle_error() to use struct dimm_info Robert Richter
2019-06-24 15:09 ` [PATCH v2 12/24] EDAC, ghes: Use standard kernel macros for page calculations Robert Richter
2019-08-02 17:04   ` James Morse
2019-08-07  9:52     ` Robert Richter
2019-06-24 15:09 ` [PATCH v2 13/24] EDAC, ghes: Add support for legacy API counters Robert Richter
2019-08-16  9:55   ` Borislav Petkov
2019-06-24 15:09 ` [PATCH v2 14/24] EDAC, ghes: Rework memory hierarchy detection Robert Richter
2019-06-24 15:09 ` [PATCH v2 15/24] EDAC, ghes: Extract numa node information for each dimm Robert Richter
2019-08-02 17:05   ` James Morse
2019-08-09 13:09     ` Robert Richter
2019-06-24 15:09 ` [PATCH v2 16/24] EDAC, ghes: Moving code around ghes_edac_register() Robert Richter
2019-06-24 15:09 ` [PATCH v2 17/24] EDAC, ghes: Create one memory controller device per node Robert Richter
2019-06-24 15:09 ` [PATCH v2 18/24] EDAC, ghes: Fill sysfs with the DMI DIMM label information Robert Richter
2019-06-24 15:09 ` [PATCH v2 19/24] EDAC, mc: Introduce edac_mc_alloc_by_dimm() for per dimm allocation Robert Richter
2019-06-24 15:09 ` [PATCH v2 20/24] EDAC, ghes: Identify dimm by node, card, module and handle Robert Richter
2019-06-24 15:09 ` [PATCH v2 21/24] EDAC, ghes: Enable per-layer reporting based on card/module Robert Richter
2019-06-24 15:09 ` [PATCH v2 22/24] EDAC, ghes: Move struct member smbios_handle to struct ghes_dimm_info Robert Richter
2019-06-24 15:09 ` [PATCH v2 23/24] EDAC, Documentation: Describe CPER module definition and DIMM ranks Robert Richter
2019-06-24 15:09 ` [PATCH v2 24/24] EDAC, ghes: Disable legacy API for ARM64 Robert Richter
2019-06-26  9:33   ` James Morse
2019-06-26 10:11     ` Robert Richter
2019-08-02  7:58 ` [PATCH v2 00/24] EDAC, mc, ghes: Fixes and updates to improve memory error reporting Robert Richter

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