I am issuing DIAGNOSE 8 on my z/os image under VM (z/vm) to do a QUERY VIRTUAL 
DASD.  It works—up to a certain point:

The QUERY VIRTUAL DASD command returns (for me) 38617 (decimal) bytes, 
according to the CC=0 after the DIAGNOSE 8 command.  My buffer is large enough 
to accommodate this.  I have tried several different sub-pools of storage.  I 
PGSER FIX the buffer pages.  I do a SYSEVENT DONTSWAP.  I do a LRA of the 
virtual address of the start of the buffer.  The DIAGNOSE completes CC=0. But, 
in my buffer, I am only seeing the first page (4095) bytes of the output.  

My question: I don’t see any documented restriction in the VM manuals that 
limits the DIAGNOSE 8 output buffer to 4K (rather the limitation is the 
architecture limit depending on your amode.) The z/vm manuals say the buffer 
can cross page boundaries.  So is there a way to force the real storage 
addresses of the page-fixed pages to be consecutive?  According to the diagnose 
8 doc., the buffer needs to be in guest-real storage, hence the LRA.  And it is 
working for the first 4k page.

Thank you for any insight you can provide. 

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