Date: Tue, 3 Jan 2023 06:27:15 -0700 From: "Edward Sanford Sutton, III" <mirror176@hotmail.com> To: stable@freebsd.org Subject: Re: Memory question Message-ID: <CO1PR11MB4770B960947484BD5E13D38CE6F49@CO1PR11MB4770.namprd11.prod.outlook.com> In-Reply-To: <20230103140404.5f71b0ad@elg.hjerdalen.lokalnett> References: <20230103140404.5f71b0ad@elg.hjerdalen.lokalnett>
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On 1/3/23 06:04, Eivind Nicolay Evensen wrote: > Hello. > > This might be more related to a bios setting or issue, but I hope > somebody can give me hints in the right direction to remedy or > at least diagnose this issue further. > > I installed more memory in one machine and now I see this > in dmesg: > > real memory = 25769803776 (24576 MB) > avail memory = 8237150208 (7855 MB) > > Real should be right, from before there were two 4 GB dimms in there, > and I inserted two more 8 GB ones. > > Transcribed from BIOS: > > DIMM(s) 1 2 3 4 > Installed Size 8192 8192 4096 4096 > Enabled Size 8192 8192 4096 4096 > Total Size 24576 > > I was wondering if the reason could be that this machine has been updated > since older versions and bootloader may be old or whatever, so I also tried > booting a linux. However, that also only uses 8 GB, and says (at least in a > way I understand) less about what it can really see. > > This is amd64 FreeBSD 13.1. > > Is there any way I can use the rest of the memory? Or at least find out > which dimms it is actually using? > > I agree. A BIOS update may also impact on what memory is supported too. It is usually for the better bot not always. Some memory uses fewer but more dense chips while others use more but less dense memory chips and which is supported can vary. Sometimes a memory manufacturer revises a stick and it may alter its compatibility too. You can also attempt to remove 1 to 3 sticks to see how it is handling the 8GB modules. They may have incompatible specifications where the system may stop booting if you do not have a 4GB stick in or even depending which slot it is in. If something is only a little out of tolerance then you may be able to try different sticks in different slots to bring them online. I usually recommend checking memory manufacturers for what they will claim they tested their memory modules with instead of the motherboard manufacturer as motherboard manufacturers do not test all sticks out there (=unnecessarily small compatibility list) and do not usually update their compatibility chart as BIOS updates and different CPU's built in memory controllers impact it. If you lookup specs for your related memory controller, you may find it has a limited amount of RAM supported. It is doubtful, though not impossible, that a BIOS update will bypass such a limitation. For Intel processors I usually just do a google search for ark + processor model to see max supported memory. intel.com ark pages are where you find processor specifications in an easy layout for their chips. Wish I knew of comparable lookups for AMD, ARM, etc.
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