> From: Christopher Schultz [mailto:ch...@christopherschultz.net] > Subject: Re: Tomcat dies suddenly > > 1. 32-bit Linux didn't support 64GiB of system memory, which it does
I didn't make it clear: this is not a software issue, it's the way the x86 architecture works for addressing memory over 4 GB. (Like the man said, "Who would ever need more than 64k?") > 2. Processes used direct-memory addressing, which they don't It's not a problem for user code, but rather for the privileged OS code that has to manage the memory space. > 3. All kernel structures must reside in <4GiB memory space (maybe > true?) No, it's generally not the Linux kernel structures, it's the ones required by the hardware - paging and I/O stuff, IIRC. (It's been awhile since I've tried to do anything interesting on a 32-bit platform.) > 4. The kernel was too stupid to move it's structures when necessary There are some that the standard Linux kernel won't move even on 64-bit systems (which causes us a great deal of pain during dynamic reconfiguration). > 6. Carl was using 32-bit Linux, which he isn't :( Correct, which made the whole point moot, so I'm not sure why Dan even brought it up. > AFAIK, 64-bit Linux has a wide-open memory addressing scheme. Maybe it > considers everything under 17 billion GiB to be "low memory", now :) No, the hardware restrictions don't exist in 64-bit mode. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers.
