Differences

This shows you the differences between two versions of the page.

--- userdoc:faq [2015/12/20 16:28]
abelbeck [Only up to 3 GB RAM is recognized]
+++ userdoc:faq [2015/12/20 16:33]
abelbeck [Only up to 3 GB RAM is recognized]
@@ Line 19: / Line 19: @@
 For 32-bit (non-PAE enabled) Linux, the maximum addressable user-space RAM is around 3 GB.  This is the case for all AstLinux board types except x86_64 based images.
-For 64-bit (x86_64) Linux, the maximum addressable RAM is only limited by your hardware, so you would expect to see about 4 GB with 4 GB RAM installed, but with the AstLinux system, the bootloader is RUNNIX (a 32-bit, non-PAE enabled Linux Kernel) which is common across all AstLinux board types.  As it turns out with RUNNIX, the "BIOS-provided physical RAM map" is trimmed to 3 GB, and that trimmed RAM map is passed on to the 64-bit x86_64 AstLinux image (via ''kexec'').
+For 64-bit (x86_64) Linux, the maximum addressable RAM is only limited by your hardware, so you would expect to see about 4 GB with 4 GB RAM installed, but with the AstLinux system, the bootloader is RUNNIX (a 32-bit, non-PAE enabled Linux Kernel) which is common across all AstLinux board types.  As it turns out with RUNNIX, the "BIOS-provided physical RAM map" is trimmed to 3 GB, and that trimmed RAM map is passed on to the 64-bit x86_64 AstLinux image (via ''kexec''), thereby also limiting the x86_64 image to 3 GB of usable RAM.
 The AstLinux developers have demonstrated that if the RUNNIX bootloader was compiled with a 32-bit, PAE enabled Linux Kernel, the "BIOS-provided physical RAM map" is not trimmed and the kexec'ed 64-bit x86_64 AstLinux image sees all the RAM.  Unfortunately the net5501 and alix hardware are not PAE capable.