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Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table
From: |
Kani, Toshimitsu |
Subject: |
Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table |
Date: |
Fri, 28 Jul 2017 20:19:15 +0000 |
On Fri, 2017-07-28 at 13:45 -0600, Ross Zwisler wrote:
> On Fri, Jul 28, 2017 at 11:11:10AM -0700, Dan Williams wrote:
> > On Fri, Jul 28, 2017 at 11:04 AM, Ross Zwisler
> > <address@hidden> wrote:
:
> > Do you need that informationin e820? Linux effectively ignores
> > type-7. As long as the range is treated as reserved it's not clear
> > that you need the e820 entry. We also infect the persistent type
> > back into the memory map when the NFIT driver loads. /proc/iomem
> > should show the right data.
>
> [ Adding Linda & Toshi to see if they have an opinion. ]
>
> I guess maybe we don't need it. Yep, /proc/iomem looks good:
>
> # cat /proc/iomem
> 00000000-00000fff : Reserved
> 00001000-0009fbff : System RAM
> ...
> 100000000-23fffffff : System RAM
> 240000000-a3fffffff : Persistent Memory
> 240000000-a3fffffff : namespace0.0
>
> I was just worried that this was an inconsistency between the way
> that virtual NVDIMMs are presented vs the way that they will be
> presented on bare metal. I at least look at the e820 table to get my
> bearings of how memory is laid out - maybe I just need to look at
> /proc/iomem instead?
FW should present a persistent memory range in e820 or UEFI memory
descriptor table. So, it's a good practice for QEMU to do it as well.
That said, the NFIT driver inserts a persistent memory range to the
kernel IO resource table from NFIT, so we are OK without this info.
Yes, /proc/iomem shows how the resources are managed by the kernel.
Thanks,
-Toshi
- [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Ross Zwisler, 2017/07/28
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Dan Williams, 2017/07/28
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Ross Zwisler, 2017/07/28
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Dan Williams, 2017/07/28
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table,
Kani, Toshimitsu <=
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Haozhong Zhang, 2017/07/29
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Ross Zwisler, 2017/07/31
- Re: [Qemu-devel] QEMU NVDIMM as type 7 in e820 table, Igor Mammedov, 2017/07/31