from the kernel config menu system: <stuff> CONFIG_NOHIGHMEM
Linux can use up to 64 Gigabytes of physical memory on x86 systems. However, the address space of 32-bit x86 processors is only 4 Gigabytes large. That means that, if you have a large amount of physical memory, not all of it can be "permanently mapped" by the kernel. The physical memory that's not permanently mapped is called "high memory". If you are compiling a kernel which will never run on a machine with more than 960 megabytes of total physical RAM, answer "off" here (default choice and suitable for most users). This will result in a "3GB/1GB" split: 3GB are mapped so that each process sees a 3GB virtual memory space and the remaining part of the 4GB virtual memory space is used by the kernel to permanently map as much physical memory as possible. If the machine has between 1 and 4 Gigabytes physical RAM, then answer "4GB" here. If more than 4 Gigabytes is used then answer "64GB" here. This selection turns Intel PAE (Physical Address Extension) mode on. PAE implements 3-level paging on IA32 processors. PAE is fully supported by Linux, PAE mode is implemented on all recent Intel processors (Pentium Pro and better). NOTE: If you say "64GB" here, then the kernel will not boot on CPUs that don't support PAE! The actual amount of total physical memory will either be auto detected or can be forced by using a kernel command line option such as "mem=256M". (Try "man bootparam" or see the documentation of your boot loader (grub, lilo or loadlin) about how to pass options to the kernel at boot time.) If unsure, say "off". </stuff> so i guess if you compile your own kernel *with* himem support, you should be able to use up to 64gb of ram (wow). ...hope that helps On January 21, 2003 11:09 am, Robert Adkins wrote: > John, > > I believe, like in Windows, you need to have specific support for High > Memory Architecture (HMA) when using Intel 32-bit Processors, which is > what I believe is in your Compaq Proliant. > > You will likely have to compile a custom Linux Kernel to support that > High Memory Architecture. Unfortunately, I cannot say for sure as I have > never had the opportunity to work with such equipment, I have only read > about such hardware. > > I believe you could get an answer as to how to configure a kernel for > your HMA equipment on a kernel mailing list. > > Regards, > Robert Adkins II > IT Manager/Buyer > Impel Industries, Inc. > Ph. 586-254-5800 > Fx. 586-254-5804 > > > -----Original Message----- > From: Turner, John [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, January 21, 2003 10:18 AM > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; Robert Adkins > Subject: Max amount of RAM in 7.2 question > > > > > Greetings - > > I've scoured Google and redhat.com most of the morning for a specific > answer, but haven't found it. Hopefully someone here will have it. > > I have a Compaq ProLiant server with RH 7.2 SMP (2.4.9-31smp kernel). Up > until this morning, it had 1.25 GB of RAM. This morning I installed 6 GB > RAM, replacing the existing 1.25 GB. The hardware supports 6 GB, and 6 > GB > shows up fine in the BIOS POST. > > However, dmesg, /proc/meminfo, and "free -m" shows that only 4 GB was > picked > up when the server was restarted. > > Is 4 GB a hard maximum limit for 7.2? Is there a hard maximum limit, and > if > so, what is it? > > I did find something on redhat.com that said I could use "mem=XXM" at > boot > to tell the kernel that there is 6 GB there and not just 4. Is that > correct? I would pass "mem=6144M" to the kernel at boot? > > - John > > ============================================ > John Turner > [EMAIL PROTECTED] | 248-488-3466 > Advertising Audit Service > http://www.aas.com -- redhat-list mailing list unsubscribe mailto:[EMAIL PROTECTED]?subject=unsubscribe https://listman.redhat.com/mailman/listinfo/redhat-list
