Chanoch (Ken) Bloom wrote: > On Tue, 2009-02-03 at 23:49 -0800, Bill Broadley wrote: >> Chanoch (Ken) Bloom wrote: >>> On Tue, 2009-02-03 at 10:28 -0800, Bill Broadley wrote: >>>> Chanoch (Ken) Bloom wrote: >>>>> I'm upgrading an x86 >>>> Not x86-64? >>> There's two machines with this problem. One is really an x86. The other >>> is an amd64, but it's running a totally 32-bit system since it shares >>> home directories by NFS with the first machine (and a couple other >>> 32-bit only machines). >> There is no problem use a 64 bit NFS server and a 32 bit NFS client. > > No there isn't, but when people are compiling binaries for one it can > can become confusing if they log in on the other and things don't work.
Ah, certainly true. I just keep users off the nfs server ;-). >>> addressable memory should go along for the ride because it's convenient >> Addressable memory isn't a particularly good one, after all the last 5 >> generations or so of intel chips could address 64GB, but only had 32 bit >> pointers (4GB worth). > > Sorry. I meant the memory addressable by a userspace process. userspace can use PAE to directly access 64GB, some server applications like oracle. >>> to do it that way, but note: >>> * an int on amd64 gcc is 32 bits. It's a long that's 64 bits. >> Indeed... although that's a language thing more than anything else. GCC also >> supports 128 bit floats (long double), but that doesn't really say anything >> about the hardware. >> >>> * The DOS memory model (*sticks out tongue*) used 16-bit pointers >>> on 16-bit processors, but addressed 1MB of RAM by the use of a >>> segment register to choose which "paragraph" of memory pointers >>> would refer to. >> Right, much like PAE. Instead of a segment register they play tricks with >> the >> page tables. Hopefully 64 bit pointers will prevent any new hacks in there >> area. Lets so most system max out at around 8 Dimms. 2^64 bytes/8 = 2^61 >> bytes. So until something bigger than 2048 Petabyte dimms become common we >> should be safe. Maybe then ZFS will makes sense ;-) > > As I said above, I was referring to process-addressible memory. PAE is > an issue clearly confined to kernel space. The DOS memory model was in > what passed for userspace. Applications can ignore PAE, but they can also uses it in user space. Microsoft provides a AWE (address windowing extensions) to use it... it's very much like the segment register of old. _______________________________________________ vox-tech mailing list [email protected] http://lists.lugod.org/mailman/listinfo/vox-tech
