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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
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
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'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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