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authorRalf Baechle <ralf@linux-mips.org>1997-04-29 21:13:14 +0000
committer <ralf@linux-mips.org>1997-04-29 21:13:14 +0000
commit19c9bba94152148523ba0f7ef7cffe3d45656b11 (patch)
tree40b1cb534496a7f1ca0f5c314a523c69f1fee464 /Documentation/memory.txt
parent7206675c40394c78a90e74812bbdbf8cf3cca1be (diff)
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+There are several classic problems related to memory on Linux
+systems.
+
+ 1) There are some buggy motherboards which cannot properly
+ deal with the memory above 16MB. Consider exchanging
+ your motherboard.
+
+ 2) You cannot do DMA on the ISA bus to addresses above
+ 16M. Most device drivers under Linux allow the use
+ of bounce buffers which work around this problem. Drivers
+ that don't use bounce buffers will be unstable with
+ more than 16M installed. Drivers that use bounce buffers
+ will be OK, but may have slightly higher overhead.
+
+ 3) There are some motherboards that will not cache above
+ a certain quantity of memory. If you have one of these
+ motherboards, your system will be SLOWER, not faster
+ as you add more memory. Consider exchanging your
+ motherboard.
+
+ 4) Linux will not currently detect above 64M of RAM,
+ regardless of how much memory is actually installed.
+
+All of these problems can be addressed with the "mem=XXXM" boot option
+(where XXX is the size of RAM to use in megabytes). Adding this boot
+option to your boot loader can help Linux see more than 64M. It can
+also tell Linux to use less memory than is actually installed.
+
+See the documentation of your boot loader (LILO, loadlin, etc.) about
+how to pass options to the kernel.
+
+There are other memory problems which Linux cannot deal with. Random
+corruption of memory is usually a sign of serious hardware trouble.
+Try:
+
+ * Reducing memory settings in the BIOS to the most conservative
+ timings.
+
+ * Adding a cooling fan.
+
+ * Not overclocking your CPU.
+
+ * Having the memory tested in a memory tester or exchanged
+ with the vendor.
+
+ * Exchanging your CPU, cache, or motherboard for one that works.
+
+ * Disabling the cache from the BIOS.
+
+ * Try passing the "mem=4M" option to the kernel to limit
+ Linux to using a very small amount of memory.
+
+
+Other tricks:
+
+ * Try passing the "no-387" option to the kernel to ignore
+ a buggy FPU.
+
+ * Try passing the "no-hlt" option to disable the potentially
+ buggy HLT instruction in your CPU.