1There are several classic problems related to memory on Linux 2systems. 3 4 1) There are some buggy motherboards which cannot properly 5 deal with the memory above 16MB. Consider exchanging 6 your motherboard. 7 8 2) You cannot do DMA on the ISA bus to addresses above 9 16M. Most device drivers under Linux allow the use 10 of bounce buffers which work around this problem. Drivers 11 that don't use bounce buffers will be unstable with 12 more than 16M installed. Drivers that use bounce buffers 13 will be OK, but may have slightly higher overhead. 14 15 3) There are some motherboards that will not cache above 16 a certain quantity of memory. If you have one of these 17 motherboards, your system will be SLOWER, not faster 18 as you add more memory. Consider exchanging your 19 motherboard. 20 21All of these problems can be addressed with the "mem=XXXM" boot option 22(where XXX is the size of RAM to use in megabytes). 23It can also tell Linux to use less memory than is actually installed. 24If you use "mem=" on a machine with PCI, consider using "memmap=" to avoid 25physical address space collisions. 26 27See the documentation of your boot loader (LILO, loadlin, etc.) about 28how to pass options to the kernel. 29 30There are other memory problems which Linux cannot deal with. Random 31corruption of memory is usually a sign of serious hardware trouble. 32Try: 33 34 * Reducing memory settings in the BIOS to the most conservative 35 timings. 36 37 * Adding a cooling fan. 38 39 * Not overclocking your CPU. 40 41 * Having the memory tested in a memory tester or exchanged 42 with the vendor. Consider testing it with memtest86 yourself. 43 44 * Exchanging your CPU, cache, or motherboard for one that works. 45 46 * Disabling the cache from the BIOS. 47 48 * Try passing the "mem=4M" option to the kernel to limit 49 Linux to using a very small amount of memory. Use "memmap="-option 50 together with "mem=" on systems with PCI to avoid physical address 51 space collisions. 52 53 54Other tricks: 55 56 * Try passing the "no-387" option to the kernel to ignore 57 a buggy FPU. 58 59 * Try passing the "no-hlt" option to disable the potentially 60 buggy HLT instruction in your CPU. 61