From: "Luck, Tony" <tony.luck@intel.com>
To: Jean Delvare <jdelvare@suse.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-nvdimm@lists.01.org, Aristeu Rozanski <aris@redhat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-acpi@vger.kernel.org, Qiuxu Zhuo <qiuxu.zhuo@intel.com>,
Borislav Petkov <bp@alien8.de>, Lv Zheng <lv.zheng@intel.com>,
Borislav Petkov <bp@suse.de>, Len Brown <lenb@kernel.org>
Subject: Re: [PATCH 4/5] firmware: dmi: Add function to look up a handle and return DIMM size
Date: Fri, 9 Mar 2018 15:03:58 -0800 [thread overview]
Message-ID: <20180309230357.iz7fx47qywx4ijnj@agluck-desk> (raw)
In-Reply-To: <20180309112053.20605672@endymion>
On Fri, Mar 09, 2018 at 11:20:53AM +0100, Jean Delvare wrote:
> > + else if (size & 0x8000)
> > + bytes = (u64)(size & 0x7fff) << 10;
> > + else if (size != 0x7fff)
> > + bytes = (u64)size << 20;
> > + else
> > + bytes = (u64)get_unaligned((u32 *)&d[0x1C]) << 20;
> > +
> > + dmi_memdev[nr].size = bytes;
>
> I'm curious, do you really need to know the amount of memory to the
> byte? The SMBIOS specification itself does not support granularity
> under 1 kB. I would be very surprised if any machine running Linux
> today has memory modules under 1 MB. If storing in MB you wouldn't need
> a u64...
I got side-tracked reading the standard with the ancient ways
used to report size back in the day when kilobytes was a
plausible unit. So I wrote code that covers all the crazy
cases. Persistant DIMMs have sizes measured in gigabytes.
I should stop worrying about "0" vs. "fffffff" and just treat
the old cases as errors and simplify the code to be:
u32 mbytes;
if (size == 0 || (size & 0x8000))
mbytes = 0;
if (size != 0x7fff)
mbytes = size;
else
mbytes = get_unaligned((u32 *)&d[0x1C]);
Then I can use 32-bit throughout this and patch 5.
Thanks for the review.
-Tony
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next prev parent reply other threads:[~2018-03-09 22:57 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 19:58 [PATCH 0/5] Teach EDAC about non-volatile DIMMs and add partial support to skx_edac Tony Luck
2018-02-22 19:58 ` [PATCH 1/5] EDAC: Drop duplicated array of strings for memory type names Tony Luck
2018-02-22 19:58 ` [PATCH 2/5] edac: Add new memory type for non-volatile DIMMs Tony Luck
2018-02-22 19:58 ` [PATCH 3/5] acpi, nfit: Add function to look up nvdimm device and provide SMBIOS handle Tony Luck
2018-02-28 17:36 ` Ross Zwisler
2018-02-28 18:48 ` Borislav Petkov
2018-02-22 19:58 ` [PATCH 4/5] firmware: dmi: Add function to look up a handle and return DIMM size Tony Luck
2018-03-09 10:20 ` Jean Delvare
2018-03-09 23:03 ` Luck, Tony [this message]
2018-03-10 13:22 ` Jean Delvare
2018-03-12 16:46 ` Luck, Tony
2018-02-22 19:58 ` [PATCH 5/5] EDAC, skx_edac: Detect non-volatile DIMMs Tony Luck
2018-03-09 10:38 ` Jean Delvare
2018-02-28 13:04 ` [PATCH 0/5] Teach EDAC about non-volatile DIMMs and add partial support to skx_edac Borislav Petkov
2018-02-28 13:59 ` Dan Williams
2018-03-12 18:24 ` [PATCH 0/5 V3] " Tony Luck
2018-03-12 18:24 ` [PATCH 1/5] EDAC: Drop duplicated array of strings for memory type names Tony Luck
2018-03-12 18:24 ` [PATCH 2/5] edac: Add new memory type for non-volatile DIMMs Tony Luck
2018-03-12 18:24 ` [PATCH 3/5] acpi, nfit: Add function to look up nvdimm device and provide SMBIOS handle Tony Luck
2018-03-12 18:24 ` [PATCH 4/5] firmware: dmi: Add function to look up a handle and return DIMM size Tony Luck
2018-03-13 9:43 ` Jean Delvare
2018-03-12 18:24 ` [PATCH 5/5] EDAC, skx_edac: Detect non-volatile DIMMs Tony Luck
2018-03-13 9:59 ` Jean Delvare
2018-03-13 15:59 ` Luck, Tony
2018-03-13 16:16 ` Jean Delvare
2018-03-14 12:00 ` Borislav Petkov
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