From: Toshi Kani <toshi.kani@hpe.com>
To: Dan Williams <dan.j.williams@intel.com>,
Yigal Korman <yigal@plexistor.com>
Cc: Toshi Kani <toshi.kani@hp.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: Legacy NVDIMM-F over EFI
Date: Tue, 17 May 2016 10:47:07 -0600 [thread overview]
Message-ID: <1463503627.27137.167.camel@hpe.com> (raw)
In-Reply-To: <CAPcyv4ioeGGe3ujkpytzJKZHDVawX95KtrFEmBvO2oaB_j_RqA@mail.gmail.com>
On Tue, 2016-05-17 at 08:57 -0700, Dan Williams wrote:
> On Tue, May 17, 2016 at 8:36 AM, Yigal Korman <yigal@plexistor.com>
> wrote:
> >
> > Hi all,
> > I've got a couple of legacy 'type 12' NVDIMM-F modules in our lab I've
> > been successfully testing.
> > Recently I moved them to a new system where EFI bootloader is used
> > (CentOS 7 installed with EFI) and was surprised to see that they're
> > not identified as legacy 'type 12' persistent memory, are not caught
> > by the 'nd_pmem' driver and I don't get /dev/pmemX devices.
> > They show as 'type 7' in the E820 map and 'Persistent memory' in
> > /proc/iomem.
> > Is this the intended behavior? shouldn't they be identified as legacy
> > if they don't have NFIT?
>
> If the BIOS identifies it as type-7 it is broken, as far as Linux is
> concerned, if does not also export an NFIT with an ACPI0012 device.
> One would hope there are no new BIOS images being produced that use
> type-12...
On an EFI system and a kernel with CONFIG_EFI_STUB set, the kernel uses EFI
memory table, instead of e820. So, e820 type-12 cannot be conveyed to the
kernel.
Since this EFI BIOS is broken as Dan pointed out, you might want to try
booting from a kernel with CONFIG_EFI_STUB unset to see if the kernel gets
e820 type-12. (Note, if e820 is set to type-7, this would lead the kernel
to overwrite data in NVDIMM due to a bug in grub.)
-Toshi
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next prev parent reply other threads:[~2016-05-17 16:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-17 15:36 Legacy NVDIMM-F over EFI Yigal Korman
2016-05-17 15:57 ` Dan Williams
2016-05-17 16:19 ` Jeff Moyer
2016-05-17 16:30 ` Yigal Korman
2016-05-17 16:33 ` Dan Williams
2016-05-19 7:28 ` Yigal Korman
2016-05-19 13:54 ` Dan Williams
2016-05-19 16:37 ` Dan Williams
2016-05-17 16:47 ` Toshi Kani [this message]
2016-05-17 17:00 ` Toshi Kani
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