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Hex Dec Type/Val Lng Label (dup) Comments
---- ---- --------- ---- -------------- --------
0000 0 Structure SEGG z/Architecture Segment Table Entry
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 Word 0 of STE Bits 0-31 of PTO
0004 4 Signed 4 SEG64W1 Word 1 of STE
0004 4 Bitstring 1 SEG64W10 Bits 32-39 of PTO or SFAA
0005 5 Bitstring 1 SEG64W11 Bits 40-47 of PTO or Bits 40-43
of SFAA, plus bit 44-46 reserved
bit 47 - ACCF-validity control
0006 6 Bitstring 1 SEGGSTA2 Bits 48-52 of PTO, plus the
following bits: non-EDAT: bits
48-52 of PTO, plus bit 53 -
ignored bit 54 - Page protection
bit bit 55 - ignored EDAT: bit
48-51 Access-Control bits bit 52
- Fetch Protection bit 53 - 0,
use non-EDAT fmt 1, use EDAT
format bit 54 - DAT protection
bit bit 55 - IEP protection bit
1111 .... SEGGACC X'F0' SEGGACC Access-Control bits
.... 1... SEGGFETP X'08' SEGGFETP Fetch-Protection
bit
.... .1.. SEGGFORM X'04' SEGGFORM Format Control bit
.... ..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. .... 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' 64-bit mask
X'FFFFFFFFFFFFFF800'
SEGGSTAT SEGGPTMH X'FFFFFFFF' SEGGPTMH Isolate
page-table origin - High
SEGGSTAT SEGGPTML X'FFFFF800' SEGGPTML Isolate
page-table origin - Low 64-bit
mask X'FFFFFFFF80000000'
SEGGSTAT SEGG2GMH X'FFFFFFFF' SEGG2GMH Isolate STE
bits which must be zero in a
<2G STE - High
.... .... SEGG2GML X'80000000' SEGG2GML Isolate STE
bits which must be zero in a
<2G STE - Low 64-bit mask
X'0000000000000200' 32-bit high
X'00000000'
SEGGSTAT SEGGPROM X'00000200' SEGGPROM Isolate
segment page protect bit 64-bit
mask X'0000000000000100' 32-bit
high X'00000000'
SEGGSTAT SEGGIEPM X'00000100' SEGGIEPM Isolate
segment IEP protect bit (when
FC=1) 64-bit mask
X'0000000000000020' 32-bit high
X'00000000'
..1. .... SEGGINVM X'00000020' SEGGINVM Isolate
invalid bit 64-bit mask
X'0000000000000010' 32-bit high
X'00000000'
...1 .... SEGGCOMM X'00000010' SEGGCOMM Isolate
common-segment bit Notes : Since
segment tables may be longer (up
to 16K) than their boundary
alignment (4K), a STO can not be
computed from an STE address via
a mask.
...1 .1.. SEGGSHFT 20 SEGGSHFT Bits to shift by to
convert between segment number
and virtual address.
SEGGSTAT SEGGPTUN 2048 SEGGPTUN Number of bytes in
a page-table. All page tables are
"full" page tables containing 256
8 byte entries, representing 1M
of virtual storage.
.... 1.11 SEGGPTUS 11 SEGGPTUS Number of bits to
shift left in order to multiply
by SEGGPTUN.
.... 1... SEGGPXNUM 8 SEGGPXNUM Number of bits in a
PX
1111 1111 SEGGPXRIT X'FF' SEGGPXRIT Mask to isolate a
right- justified PX
.... 1..1 SEGGPXDS 12-3 SEGGPXDS Bits to shift to
convert between an isolated page
index and the displacement into
the page table of applicable 8
byte PTE.
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