My experience is that under VM6.1 multiple segments (which must be less than or equal to 2GB individually) may be mapped to a space greater than 2GB. We have been working with this for sharing application binaries on our Linux hosts and met with success. They do have to obey the megabyte boundaries.
I believe it can be done on 5.4 as well but do not have experience with this, myself. On Wed, May 25, 2011 at 12:37 AM, Kris Buelens <kris.buel...@gmail.com>wrote: > Saved segments are based on the architected segments found in the z > architecture. A segment is a whole number of megabytes. > So, > > FILE FILENAME FILETYPE BEGPAG ENDPAG TYPE CL #USERS > 0054 ITMV1A DCSSG 0000000280000 00000002FFE00 SR A 00000 > uses segments 280 through 2FF (that is; it covers addresses 280000 through > 2FFFFF) > and that overlaps the beginning address of > 0055 ITMV1B DCSSG 00000002FFE01 000000037FD00 SR A 00000 > Change the definitions to > > FILE FILENAME FILETYPE BEGPAG ENDPAG TYPE CL #USERS > 0054 ITMV1A DCSSG 0000000280000 00000002FFFFF SR A 00000 > 0055 ITMV1B DCSSG 0000000300000 000000037FD00 SR A 00000 > and the segments will no longer overlap. > If you really must work with segments on page boundary and load them > together, you can use segment spaces and segment members: > DEFSEG ITMV1A 280000-2FFE00 SR SPACE ITM > DEFSEG ITMV1B 2FFE01-37FD00 SR SPACE ITM > The segment space named ITM would cover address range 280000-37FFFF. When > loading one member, CP will almost do as if it loads the whole space (CP > must obey to the z architecture, with segments on megabyte boundaries), the > second member can then also be loaded. But, the resultant space covers a > range > 2GB, which I think is not supported either. Segment spaces were > invented when we used to store all (or many) segments below the 16MB line, > very small when installing many program products... > I never used DCSSes above 2GB, maybe extra restrictions apply. > > > 2011/5/25 Mark Post <mp...@novell.com> > >> Cross-posted to IBMVM and Linux-390 >> >> I'm working on a project where I want an xip2 file system that is larger >> than 2GB. So, I'm trying to use the support built into z/VM and Linux to >> logically concatenate multiple DCSS into one. But, I can't seem to get it >> to work. I can load one segment or the other, but not both. The message >> that comes out on the console is >> extmem.cb0afe: ITMV1B needs used memory resources and cannot be loaded or >> queried >> >> "man extmem.cb0afe" says "You cannot load or query the DCSS because it >> overlaps with an already loaded DCSS or with the memory of the z/VM guest >> virtual machine (guest storage)." I don't believe any of those apply, but I >> need someone to tell me what to do differently, or to whom I should be >> complaining. >> >> The segments are defined as this: >> FILE FILENAME FILETYPE BEGPAG ENDPAG TYPE CL #USERS >> 0054 ITMV1A DCSSG 0000000280000 00000002FFE00 SR A 00000 >> 0055 ITMV1B DCSSG 00000002FFE01 000000037FD00 SR A 00000 >> >> The guest virtual storage is 1GB: >> #CP Q V STOR >> STORAGE = 1G >> >> The kernel was booted with a mem= value sufficient to contain the highest >> address of the ITMV1B DCSS: >> # cat /proc/cmdline >> root=/dev/disk/by-path/ccw-0.0.9300-part1 TERM=dumb mem=16384M >> BOOT_IMAGE=0 >> >> The command to allocate the two DCSS is: >> echo itmv1a:itmv1b > /sys/devices/dcssblk/add >> >> And that's where I get my error (after 2 minutes). As I said previously, >> if I try to load them individually, I can do one or the other, but not both. >> >> This is an up to date SLES11 SP1 system, running on z/VM 6.1 RSU 1003. >> Does anyone see the problem? >> >> >> Mark Post >> > > > > -- > Kris Buelens, > IBM Belgium, VM customer support >
