It would have been clearer to post that info in your own thread at
Originally Posted by vonbiber
BIOS-e820: 00000000bfdff000 - 00000000bfe00000 (usable)
Various lines up to and including that one, show you have nearly 3GB of ram mapped (by the memory controller) within the first 4GB of address space. Without PAE, that is the amount usable.
BIOS-e820: 0000000100000000 - 0000000140000000 (usable)
That line says you have another 1GB of ram outside the first 4GB of address space. You need PAE to use that (in a 32 bit kernel).
# CONFIG_NOHIGHMEM is not set
# CONFIG_HIGHMEM64G is not set
Sorry, I still don't know what config choices you should use to turn on PAE, especially how to turn it on efficiently (without also turning on the option to split the process 4GB space from the kernel 4GB space).
I'm pretty sure CONFIG_HIGHMEM64G includes turning on PAE. I suspect it also turns on other things you likely don't want. But despite a few google searches and other attempts at finding the right documentation I'm still quite confused about which config options go with which exact features (I don't have time to look into the source code for the real answer).
I do know the 4G in CONFIG_HIGHMEM4G refers to 4GB of physical address space, not 4GB of actual ram. A full 4GB of ram requires more than 4GB of physical address space and CONFIG_HIGHMEM4G does not give you that.
Anyway, you have answered syg00's concern from your thread. Your missing 1GB of memory is definitely a problem in configuring the Linux kernel. It is definitely not a problem in your BIOS or motherboard. (Having been in a bunch of these threads, I think syg00 made a good guess. It is more often a motherboard problem. But not this time.)