I have a GIGABYTE-P35-DS3L MB with 8GB installed, but my fc7 kernel "Linux ezrider 2.6.23.17-88.fc7 #1 SMP Thu May 15 00:35:10 EDT 2008 i686 i686 i386 GNU/Linux" only sees 4GB. I assume I just need to redo my kernel to handle the bigger memory. I'm asking just to make sure before I start mucking with a kernel that works beautifully, otherwise.

-- ezrider

The kernel you're looking for is the "kernel-PAE" (Physical Address Extensions). The regular kernel is only able to address 4GB, and the PAE version can handle up to 64GB. Just double check that your CPU is PAE capable, and that your package manager does not remove your current kernel (I believe yum defaults to 2 versions of each type of kernel, but don't quote me on that). If you're using grub (grub.conf), check your settings for which kernel is booted by default, and also the delay for interactive selection upon boot.

When you do your next install (support for F7 will be dropped in about a month), consider switching to the 64bit version. It handles larger amounts of memory much better than the 32bit version. There are relatively few things (now) that 32bit can do that 64bit cannot.

Especially with that much memory.
64-bit is the way to go if you have the hardware.

Thanks to all of you that responded. I looked for "pae" & I see it when I cat /proc/cpuinfo, & yet it doesn't see the 8GB. Also, two of the early boot messages are "Warning only 4GB will be used" & "Use a HIGHMEM64G enabled kernel." Does that means my only option is to go to a 64 bit kernel (e.g., FC9)?

-- ezrider

No, HIGHMEM64G is a kernel option (yet another hack on top of the HIGHMEM4G hack). Maybe Fedora offered a hugemem kernel back in FC7 days. I've never used FC, but I recall hearing about something like that.

I think there is a kernel with HUGEMEM enabled (that's another name for HIGHMEM64G), look around for it. If you don't find one, consider compiling one with it enabled. If not, then use 64-bit version.

cpuinfo is info about your cpu, not info about your kernel. You just verified your CPU supports PAE (I think it has been a long time since they made any x86 CPU that doesn't). To use PAE, you need both the CPU and the kernel to support it.

Meaning your kernel doesn't support PAE. As others have told you, HIGHMEM64G is one of the names for kernel support of PAE.

No. It doesn't even tell you whether a 64 bit kernel is an option (the lm bit in the flags in cpuinfo would tell you whether your CPU would support a 64 bit kernel).

Assuming your CPU supports it, a 64 bit kernel is one option. Depending on what mix of applications you run on that system, there might be some significant advantage to a 64 bit kernel over a 32 bit HIGHMEM64G kernel. Or there might be a small advantage to HIGHMEM64G over 64 bit. Or more likely, there would be no significant difference.

From what you have now, switching just the kernel (to HIGHMEM64G) is a smaller change. If you can't find the kernel you want pre built, building it isn't very hard.