cannot enable High Memory Support
I am trying to configure a kernel (188.8.131.52, under openSuSE 11.3) that would be able to use all my 4GB RAM (not just 3.5GB) but when I go to "Processor type and features" -> "Enable High Memory Support", as per the instructions on a lot of places I found by googling, the option is disabled (grayed out in gconfig, XXX in nconfig). A lot of other options are disabled too, for example, a subset of the options looks like this:
<*> /Dev/cpu/*/msr - Model-specific register support
<m> /Dev/cpu/*/cpuid - CPU information support
XXX High Memory Support
XXX Memory split
XXX 3G/1G user/kernel split
XXX 3G/1G user/kernel split (for full 1G low memory)
XXX 2G/2G user/kernel split
XXX 2G/2G user/kernel split (for full 2G low memory)
XXX 1G/3G user/kernel split
XXX () PAGE_OFFSET
XXX PAE (Physical Address Extension) Support
XXX Enable 1GB pages for kernel pagetables[*] nUma Memory Allocation and Scheduler Support
XXX *** NUMA (Summit) requires SMP, 64GB highmem support, ACPI ***[*] Old style AMD Opteron NUMA detection[*] ACPI NUMA detection
XXX NODES_SPAN_OTHER_NODES[*] nUMA emulation
(9) mAximum NUMA Nodes (as a power of 2)
I couldn't find any menu option in the config utilities to enable the XXXs.
I also googled for "linux kernel config disabled options", but nobody seems to have had this problem.
I guess I could just add CONFIG_HIGHMEM64G=y to .config to fix my problem in this particular case, but I'd better figure out what's wrong with my settings.
Any ideas will be appreciated.