intensely fascinating shit
Oct. 17th, 2006 04:57 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
We're using a particular Tyan board on many of the workstations at work. It maxes out at 4 RAM sticks of 1 GB each, for a total of 4 GB. However, upon booting, the OS (and memtest86) would only find 3296 MB (despite the BIOS claiming "4096 MB OK"). I updated the BIOS and that let us have 128 MB more, for a total of 3424 MB. A friendly Google search yielded information that suggested we enable the "software memory hole" in the BIOS setup; apparently, these things reserve space between 3.5 GB and 4 GB for god knows what, and enabling the setting frees that up. Upon enabling the SMH, the RAM test during bootup shows it happily counting up to 3072 MB, freezing for a second, then counting up from 4096 MB to 5120 MB, and upon reaching that, going back to display "4096 MB OK". The OS now admits to seeing all the RAM.
(Oh, and i didn't even go into the near-impossibility of making a bootable CD that included the BIOS Flash file and utility that worked. We ended up finding a floppy drive and disk rather than suffer and keep dumping coasters.)
It's a good thing that my livelihood doesn't depend on understanding computers, because god damn i hate the fuckin' things.
no subject
Date: 2006-10-18 12:49 am (UTC)Some OSs will report that you have 5GB of RAM, too. Here's what a FreeBSD 5.4 box (manually patched to get around a severe bug the FreeBSD team didn't fix til 5-STABLE or something) says it has on a SuperMicro server with 4GB of RAM:
real memory = 4831838208 (4608 MB)
avail memory = 4194848768 (4000 MB)
All in all it's pretty obnoxious behavior, but I guess it's necessary to address the additional RAM. I don't know how it works exactly, but I think I'd prefer all real RAM be remapped above 4GB so it's consistent.
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Date: 2006-10-18 12:52 am (UTC)no subject
Date: 2006-10-18 12:55 am (UTC)no subject
Date: 2006-10-18 01:28 am (UTC)no subject
Date: 2006-10-21 04:17 pm (UTC)The PCI issue is that basic PCI only has 32-bit address lines, and PC custom is to map the PCI address space straight into normal system memory space. This means that various sorts of memory and pseudo-memory resources on PCI cards has to show up somewhere below 4GB.
(RAM gets remapped above 4GB instead of PCI cards because generally remapping RAM above 4GB is much, much simpler than remapping PCI cards.)
no subject
Date: 2006-10-18 01:06 am (UTC)It's a good thing that my livelihood doesn't depend on understanding what you wrote, because god damn at least you're cute.
xoxoxo.
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Date: 2006-10-18 01:18 am (UTC)no subject
Date: 2006-10-18 04:08 am (UTC)no subject
Date: 2006-10-18 05:22 am (UTC)I've been living with this in virtual storage
Date: 2006-10-18 08:08 pm (UTC)