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Hex Dec Type/Val Lng Label (dup) Comments
---- ---- --------- ---- -------------- --------
0000 0 Structure SEG64 SEGMENT TABLE ENTRY
00FFFFFF SEGGPTMH X'FFFFFFFF' Isolate page-table
origin - High
00FFF800 SEGGPTML X'FFFFF800' Isolate page-table
origin - Low
0000F800 SEGGPTMLL X'F800' Isolate PTO - LowLow
64-bit mask X'FFFFFFFF80000000'
00FFFFFF SEGG2GMH X'FFFFFFFF' Isolate STE bits
which must be zero in a <2G
STE - High
.... .... SEGG2GML X'80000000' Isolate STE bits
which must be zero in a <2G
STE - Low
64-bit mask X'0000000000000200'
32-bit high X'00000000'
00000200 SEGGPROM X'00000200' Isolate segment page
protect bit
64-bit mask X'0000000000000100'
32-bit high X'00000000'
00000100 SEGGIEPM X'00000100' Isolate IEP segment
protect bit (FC=1)
64-bit mask X'0000000000000020'
32-bit high X'00000000'
..1. .... SEGGINVM X'00000020' Isolate invalid bit
64-bit mask X'0000000000000010'
32-bit high X'00000000'
...1 .... SEGGCOMM X'00000010' Isolate
common-segment bit
0000 0 Dbl-Word 8 SEGGENTR Segment table entry
00000008 SEGGLEN *-SEGGENTR Length of one STE
0008 8 Dbl-Word 8 SEGGNEXT (0) Next segment table entry
0000 0 Signed 4 SEG64W0 (0) Word 0 of STE Bits 0-31 of PTO
0000 0 Bitstring 1 SEG64B0 Byte 0 of STE NOTES : The
following bit definition occupies
bit 0 of the STE since there are
no more unused bits in either
SEGGSTAT or SEGGSTA2. Even though
SEGGSTA2 appears to have spare
bits, they may never be used for
segments whose PGMBK is paged
out, since that byte is used as
part of the ASA information.
1... .... SEGGSTBL X'80' SEGGSTBL A system reset
function occurred while the PGMBK
was paged out. This bit indicates
that the PGSTE entries for this
segment must all be set to stable
state when the PGMBK is next
paged in. This bit only has
meaning when SEGGINVL=1
0001 1 Bitstring 1 * (3) Bytes 1-3 of STE
0004 4 Signed 4 SEG64W1 Word 1 of STE
0004 4 Bitstring 1 * (2) Bits 32-47 of PTO
0006 6 Bitstring 1 SEGGSTA2 Bits 48-52 of PTO, plus the
following three bits:
.... ..1. SEGGPROT X'02' SEGGPROT Entire segment is
page protected
.... ...1 SEGGIEP X'01' SEGGIEP Entire segment is
IEP protected (when FC=1)
0007 7 Bitstring 1 SEGGSTAT Segment Table Entry Status
1... .... SEGGWAIT X'80' SEGGWAIT Segment has
translation requests waiting.
SEGGINVL must be = 1. In order to
enqueue a deferred STE
serialization request, CS must be
used to insist that both SEGGINVL
and SEGGTRAN are on continuously
while either turning SEGGWAIT on,
or finding it on and leaving it
on. This bit is a non-architected
software definition.
.1.. .... SEGGTRAN X'40' SEGGTRAN Segment is being
translated This bit is used by
software to serialize segment
translation. SEGGINVL must be =
1. This bit is a non-architected
software definition. Note that
TMLL is used to test SEGGINVL and
SEGGNULL at the same time. This
creates a dependency on SEGGINVL
being to the left of and in the
same halfword as SEGGNULL.
..1. .... SEGGINVL X'20' SEGGINVL Segment Table
Entry is invalid Bits 0-52 of the
Segment Table entry do NOT
contain a valid Page-Table Origin
...1 .... SEGGCOMN X'10' SEGGCOMN Common segment bit
.... 11.. SEGGTTBT X'0C' SEGGTTBT Table Type bits -
must be b'00'
.... ..1. SEGGXSTR X'02' SEGGXSTR Used by CP to
indicate that a PGMBK that
resides on XSTORE supports pages
that also reside on XSTORE. This
bit is a non-architected software
definition.
.... ...1 SEGGNULL X'01' SEGGNULL Segment cannot be
allocated for guest storage, it
is not addressable by the user.
SEGGINVL must be = 1. This bit is
a non-architected software
definition.
z/Arch segment table entry contains no page table length
information. All page tables represent a
full megabyte of virtual storage (256 page table entries).
00000014 SEGGSHFT 20 Bits to shift by to convert
between segment number and
virtual address.
00000800 SEGGPTUN 2048 Number of bytes in a
page-table. All page tables are
"full" page tables containing 256
8 byte entries, representing 1M
of virtual storage.
0000000B SEGGPTUS 11 Number of bits to shift left
in order to multiply by SEGGPTUN.
00000009 SEGGPXDS 12-3 Bits to shift to convert
between an isolated page index
and the displacement into the
page table of the applicable 8
byte PTE.
00000008 SEGGPTRM 8 Bits to shift to determine if
an invalid STE contains a PTRM
virtual address. Note that this
should be a 64-bit shift (SRAG),
as the PTRM address occupies both
words of the STE.
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