Original from  Mike Bilow  to Mario Semo on 06-10-1996
Original Subject: Toolkit 1.3 from Devcon

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  MB> selector is mapped to a 4 KB area of memory.  You cannot 
  MB> then call DosSetMem() to commit more memory than the 
  MB> allocated selector length under any version of OS/2.

  MS> and thats again WRONG! PLEASE try before you write
  MS> something. 

  MS> Under OS/2 WARP GA you CAN:

  MS>  DosAllocMem(1byte,READ/WRITE)
  MS>  DosSetMem(64K,committed) -> OK
  MS>  DosSetMem(64K+1byte committed) -> ERROR

  MS>  so, it appears as 64K IS allocated whatever you say
  MS> refering to ancient OS/2 toolkits prior to DevCon8. 

MB> What seems to happen when you call DosSetMem() to commit 
MB> residue unallocated memory is that OS/2 will commit it for 
MB> you if and only if it has not been otherwise allocated.  
MB> This is essentially an operation which works by 
MB> coincidence.  The exact point at which DosSetMem() fails is 
MB> not necessarily 64 KB, but varies somewhat unpredictably.

 Sorry Mike.. From what I can see, this is very predictable. SetMem 
will fail if the page is already commited, but in the example above it
will ALWAYS work for 16 pages, no more, no less. 

 I am still attempting to do more digging into this.. 


   Denis       

 Certified OS/2 Engineer, Certified OS/2 Instructor, Certifiable....
 All opinions are my very own, IBM has no claim upon them

.
--- Maximus/2 3.01