= Determining the !irtual !achine storage Size Execution of DIAGNOSE code X'60' allows a virtual machine to determine its size. On return, the register specified as Rx contains the virtual
machine storage size.
Execution of DIAGNOSE code X'64' controls the linkage of discontiguous
saved segments. The type of linkage that is performed depends upon the
function subcode in the register specified as Ry= Function segment in shared mode Subcode -Foo' X'04' X'08' X'OC' LOIDSYS LOIDSYS PURGESYS FINDSYS Loads a named segment in nonshared mode Releases the named segment from virtual storage
Finds the starting address of the naaed segment The register specified as Rx must contain the address of the name of
the segment. The segment name must be 8 bytes long, left justified, and
padded with trailing blanks. When the LOIDSYS diagnose function is executed, CP finds the system name table entry for the named system and builds the necessary page and swap
tables. Two sets of page and swap tables, one for each processor, are
built for each shared segment in attached processor mode unless the
naaed system was defined as unprotected. CP releases all the virtual
pages of storage that are to contain the named segment and then loads
the segment in those virtual pages. When the LOIDSYS function is
executed, CP expands the virtual machine size dynamically, if necessary. CP dlso expands the segment tables to match any expansion of virtual storage_ When LOADSYS executes successfully, the address of where
segment was loaded is returned in the register specified as
the LOIDSYS function loads a segment in shared mode, instruction and branch tracing if either was active.
the naaed Rx. When it resets
lfter a LOIDSYS function executes, the storage occupied by the naaed segment is addressable by the virtual aachine, even if that storage is
beyond the storage defined for the virtual machine. However, any
storage beyond that defined for the virtual machine and below that
defined for the named segment is not addressable. Figure 15 shows the
virtual storage that is addressable before and after the LOIDSYS function executes. CP Introduction 1-67
Before the LOADSYS 320K_.------------------_ I I I I I I , l I All Storage Addressable by Virtual ftachine I ,. CftS virtual ftachine without a la.ed Seg.ent Attached
After LOADSYS Function
_ ______ ____ _
448K_.------------------------, I Discontiguous Storage I Addressable by Virtual I ftachine .///////////////////////// . /Storage lot Addressable/ ///by Virtual ftachine//// . /////////////////////////. 320K I I l I I I I I Storage Still I I Addressable by I I Virtual ftachine I I I I , , , OK' I CftS Virtual ftachine with a la.ed Seg.ent Attached Before and After a LOADSYS Function When you save a na.ed seg.ent that is later loaded by the LOADSYS function, you .ust be sure that the addresses at which seg.ents are
saved are correct and that they do not overlay required areas of storage
in the virtual .achine. This is crucial because the LOADSYS function
invokes the PURGESYS function before it builds the new page and swap tables. CP purges all saved syste.s that are overlayed in any way by
the saved syste. it is loading. 1 condition code of 0 in the PSW indicates that the na.ed seg.ent was loaded successfully; the Rx register contains the load address. A condition code of 1 in the PSi indicates the na.ed seg.ent was loaded successfully within the defined storage of the virtual .achine.
The Rx register contains the address at which the na.ed seg.ent was loaded. The Ry register contains the ending address of the storage
released before the na.ed segment Was loaded.
Bote: CftS only allows naaed segments to be attached beyond the defined
size of the virtual .achine. A condition code of 2 in the PSi indicates the LOADSYS function did
not execute successfully. Examine the return code in the Ry register to
deter.ine the cause of the error.
Return Code ---"4--- 177 fteani,!!g Ba.ed seg.ent does not exist
Paging I/O errors When the PURGESYS function
associated page and swap is executed; CP
tables, that
releases the storage, and
were acquired when the
1-68 IB! V!/370 Syste. Logic and Problem Deter.ination--Volu.e 1
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