Re: Memory controller not showing half of the memory?

[Yazen Ghannam <yazen.ghannam@amd.com>]

On Thu, Mar 13, 2025 at 06:48:42PM +0100, reox wrote:
> 
> 
> Am 13.03.2025 um 18:31 schrieb Borislav Petkov:
> > On Thu, Mar 13, 2025 at 06:21:28PM +0100, reox wrote:
> > > Hello,
> > > 
> > > I hope it is okay to ask such a question on this mailinglist, however there
> > > is surprisingly little information on this topic (or I'm not deep enough in
> > > the matter to understand everything correctly...).
> > > 
> > > I have a server with a ASRockRack B665D4U-1L board. I'm running Debian with
> > > bookworm-backports kernel 6.12.9-1~bpo12+1.
> > > In the syslog I see the following output of EDAC:
> > > # dmesg | grep -i EDAC
> > > [    1.340448] EDAC MC: Ver: 3.0.0
> > > [    4.705255] EDAC MC0: Giving out device to module amd64_edac controller
> > > F19h_M70h: DEV 0000:00:18.3 (INTERRUPT)
> > > [    4.705262] EDAC amd64: F19h_M70h detected (node 0).
> > > [    4.705266] EDAC MC: UMC0 chip selects:
> > > [    4.705267] EDAC amd64: MC: 0:     0MB 1:     0MB
> > > [    4.705270] EDAC amd64: MC: 2:  8192MB 3:  8192MB
> > > [    4.705273] EDAC MC: UMC1 chip selects:
> > > [    4.705274] EDAC amd64: MC: 0:     0MB 1:     0MB
> > > [    4.705277] EDAC amd64: MC: 2:  8192MB 3:  8192MB
> > > 
> > > However, compare this to the real amount of memory (2×32GB):
> > > # lshw -c memory  # shorted
> > >    *-memory
> > >         size: 64GiB
> > >         capabilities: ecc
> > >         configuration: errordetection=multi-bit-ecc
> > >       *-bank:0
> > >            description: [empty]
> > >       *-bank:1
> > >            description: DIMM Synchronous Unbuffered (Unregistered) 4800 MHz
> > > (0.2 ns)
> > >            product: HMCG88MEBEA081N
> > >            vendor: SK Hynix
> > >            size: 32GiB
> > >       *-bank:2
> > >            description: [empty]
> > >       *-bank:3
> > >            description: DIMM Synchronous Unbuffered (Unregistered) 4800 MHz
> > > (0.2 ns)
> > >            product: HMCG88MEBEA081N
> > >            vendor: SK Hynix
> > >            size: 32GiB
> > > 
> > > I'm a bit confused here... Does EDAC simply miss half of the memory? Is this
> > > output correct? Or the memory controller not fully implemented / bugged in
> > > that kernel version (with the bookworm kernel it does not load EDAC at all)?
> > 						^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 
> > What does that mean, exactly?
> > 
> > Are you force-loading the module?
> 
> Sorry, that was formulated a bit sloppy... I meant that with the current
> bookworm kernel (6.1.128) there was no memory controller detected. The
> module was loaded fine but reported nothing. As far as I can tell, support
> was added only with 6.5 with commit 6c79e42 (would the expected outcome in
> my case also be 4×16GB?).
> 
> by the way, if it helps, the CPU is a "AMD Ryzen 7 PRO 8700GE w/ Radeon 780M
> Graphics".
> 
> > 
> > You could send a full dmesg...
> 
> from 6.1.128 or 6.12.9?
> 

From the latest, please.

It could be that the memory layout/assignment is slightly different on
this model group compared to others. I'll see what I can find out.

Thanks for reporting this!

Thanks,
Yazen