I wrote a short python program to extract segment table and page table entries from the ROM and dump them to files. I then analyzed these files to work out (in particular) what the virtual addresses for IO devices were. I was also interested how the MMU would set up a 256M address space with only 16M of physical ram and a small handful of IO devices, especially since the page table is fairly small (it can only map 16M given that it has 4096 entries that each map an 8K page).
First, here is my analysis of the Segmap and entries that map ram.
# Here is the SegMap, dumped by the "m" rom command # The "m" command quits after dumping 2K entries. # In other words, it only dumps the current context. # The Segmap is 16K all told, but is divided into 8 2K sections, # one for each context. # One context (2K Segmap registers) maps 2048 * 128K = 256M of address. # This is the per-process address space on a sun3 (256M) # A process only gets to use 28 bits # The map begins with 64 entries. # Each maps 128K, so this covers 64*128K = 8M of memory # (Our hardware actually has 16M, why is it not all mapped?) # After this we get 0xff entries on until address 0FE00000 # Then there are a final 16 entries with curious mapping # 16 entries maps 2M of memory # So we have a 256M address space with the first 8M mapped # to ram, and the final 2M mapped to "special things" # # the central 246M are vacant. # # In other words, only 80 Segmap values are "interesting" # and in truth only the final 16 are really interesting # Each Seg references a PMEG (a group of 16 PMAP registers) # here is the first part of the first PMEG for the RAM addresses # the rest of the PMAP registers just continue in sequence. # The control bits in the upper byte are: # Valid, Write allowed, not supervisor restricted, then a reserved bit is set # type = 00 (main memory), accessed and modified. # Presumably they are accessed and modified because a # memory diagnostic has been run on all of them. PageMap 00000000 [00]: D3000000? PageMap 00002000 [00]: D3000001? PageMap 00004000 [00]: D3000002? PageMap 00006000 [00]: D3000003? # Let's look at the PMEG for the central, prsumably invalid addresses # It looks like this. The main thing is that the upper bit is 0, # which indicates that the page is invalid PageMap 00800000 [FF]: 20000000? PageMap 00802000 [FF]: 20000000? PageMap 00804000 [FF]: 20000000? PageMap 00806000 [FF]: 20000000? PageMap 00808000 [FF]: 20000000? PageMap 0080A000 [FF]: 20000000? PageMap 0080C000 [FF]: 20000000? PageMap 0080E000 [FF]: 20000000? PageMap 00810000 [FF]: 20000000? PageMap 00812000 [FF]: 20000000? PageMap 00814000 [FF]: 20000000? PageMap 00816000 [FF]: 20000000? PageMap 00818000 [FF]: 20000000? PageMap 0081A000 [FF]: 20000000? PageMap 0081C000 [FF]: 20000000? PageMap 0081E000 [FF]: 20000000? # Finally we get the "interesting" addresses for the last 2M # I am going to analyze those PAGE map registers in their own file. # (that files is seg2.out) SegMap 0FE00000: FE? SegMap 0FE20000: FD? SegMap 0FE40000: FC? SegMap 0FE60000: FB? SegMap 0FE80000: FA? SegMap 0FEA0000: F9? SegMap 0FEC0000: FF? -- invalid SegMap 0FEE0000: F7? SegMap 0FF00000: F6? SegMap 0FF20000: F5? SegMap 0FF40000: F4? SegMap 0FF60000: F3? SegMap 0FF80000: FF -- invalid SegMap 0FFA0000: FF -- invalid SegMap 0FFC0000: FF -- invalid SegMap 0FFE0000: F8? # The Segmap in order follows: SegMap 00000000: 00? SegMap 00020000: 01? SegMap 00040000: 02? SegMap 00060000: 03? SegMap 00080000: 04? SegMap 000A0000: 05? SegMap 000C0000: 06? SegMap 000E0000: 07? SegMap 00100000: 08? SegMap 00120000: 09? SegMap 00140000: 0A? SegMap 00160000: 0B? SegMap 00180000: 0C? SegMap 001A0000: 0D? SegMap 001C0000: 0E? SegMap 001E0000: 0F? SegMap 00200000: 10? SegMap 00220000: 11? SegMap 00240000: 12? SegMap 00260000: 13? SegMap 00280000: 14? SegMap 002A0000: 15? SegMap 002C0000: 16? SegMap 002E0000: 17? SegMap 00300000: 18? SegMap 00320000: 19? SegMap 00340000: 1A? SegMap 00360000: 1B? SegMap 00380000: 1C? SegMap 003A0000: 1D? SegMap 003C0000: 1E? SegMap 003E0000: 1F? SegMap 00400000: 20? SegMap 00420000: 21? SegMap 00440000: 22? SegMap 00460000: 23? SegMap 00480000: 24? SegMap 004A0000: 25? SegMap 004C0000: 26? SegMap 004E0000: 27? SegMap 00500000: 28? SegMap 00520000: 29? SegMap 00540000: 2A? SegMap 00560000: 2B? SegMap 00580000: 2C? SegMap 005A0000: 2D? SegMap 005C0000: 2E? SegMap 005E0000: 2F? SegMap 00600000: 30? SegMap 00620000: 31? SegMap 00640000: 32? SegMap 00660000: 33? SegMap 00680000: 34? SegMap 006A0000: 35? SegMap 006C0000: 36? SegMap 006E0000: 37? SegMap 00700000: 38? SegMap 00720000: 39? SegMap 00740000: 3A? SegMap 00760000: 3B? SegMap 00780000: 3C? SegMap 007A0000: 3D? SegMap 007C0000: 3E? SegMap 007E0000: 3F? SegMap 00800000: FF? SegMap 00820000: FF? SegMap 00840000: FF? .... .... SegMap 0FDA0000: FF? SegMap 0FDC0000: FF? SegMap 0FDE0000: FF? SegMap 0FE00000: FE? SegMap 0FE20000: FD? SegMap 0FE40000: FC? SegMap 0FE60000: FB? SegMap 0FE80000: FA? SegMap 0FEA0000: F9? SegMap 0FEC0000: FF? SegMap 0FEE0000: F7? SegMap 0FF00000: F6? SegMap 0FF20000: F5? SegMap 0FF40000: F4? SegMap 0FF60000: F3? SegMap 0FF80000: FF? SegMap 0FFA0000: FF? SegMap 0FFC0000: FF? SegMap 0FFE0000: F8? # THE END# Here is my analysis of the final 2M of our address space
SegMap 0FE00000: FE? SegMap 0FE20000: FD? SegMap 0FE40000: FC? SegMap 0FE60000: FB? SegMap 0FE80000: FA? SegMap 0FEA0000: F9? SegMap 0FEC0000: FF? -- invalid SegMap 0FEE0000: F7? SegMap 0FF00000: F6? SegMap 0FF20000: F5? SegMap 0FF40000: F4? SegMap 0FF60000: F3? SegMap 0FF80000: FF -- invalid SegMap 0FFA0000: FF -- invalid SegMap 0FFC0000: FF -- invalid SegMap 0FFE0000: F8? # Note in the following, the value in square brackets is the Segmap # entry that got us to each PMEG, which is handy. # Note also that the monitor "p" command does not go through # the PMAP in order. It goes through virtual addresses in order. # Depending on how the MMU is set up, this may lead us to the # same PMAP entry multiple times, as it does for invalid sections # This first PMEG is especially interesting as it contains entries # with the type bits = 01 (IO!) # D7 = valid, writeable, not super, type 01, modified and accessed # D6 = valid, writeable, not super, type 01, accessed, not modified # D4 = valid, writeable, not super, type 01, not accessed, not modified # D0 = valid, writeable, not super, type 00, not accessed, not modified # F0 = valid, writeable, super, type 00, not accessed, not modified PageMap 0FE00000 [FE]: D7000000? -- IO: Kb / mouse PageMap 0FE02000 [FE]: D7000010? -- IO: SCC PageMap 0FE04000 [FE]: D6000020? -- IO: EEPROM PageMap 0FE06000 [FE]: D7000030? -- IO: TOD 7170 PageMap 0FE08000 [FE]: D7000040? -- IO: Mem error regs PageMap 0FE0A000 [FE]: D7000050? -- IO: Interrupt register PageMap 0FE0C000 [FE]: D7000060? -- IO: Intel ethernet PageMap 0FE0E000 [FE]: D4000000? -- IO: Kb/ mouse !! PageMap 0FE10000 [FE]: D4000090? -- IO: AMD lance ethernet PageMap 0FE12000 [FE]: D40000A0? -- IO: scsi PageMap 0FE14000 [FE]: D40000E0? -- IO: encryption PageMap 0FE16000 [FE]: D40000F0? -- IO: ECC memory regs PageMap 0FE18000 [FE]: D007F980? PageMap 0FE1A000 [FE]: D007F8E0? PageMap 0FE1C000 [FE]: F0000FEE? PageMap 0FE1E000 [FE]: F0000FEF? # D0 = valid, writeable, not super, type 00, not accessed, not modified PageMap 0FE20000 [FD]: D007F800? PageMap 0FE22000 [FD]: D007F801? PageMap 0FE24000 [FD]: D007F802? PageMap 0FE26000 [FD]: D007F803? PageMap 0FE28000 [FD]: D007F804? PageMap 0FE2A000 [FD]: D007F805? PageMap 0FE2C000 [FD]: D007F806? PageMap 0FE2E000 [FD]: D007F807? PageMap 0FE30000 [FD]: D007F808? PageMap 0FE32000 [FD]: D007F809? PageMap 0FE34000 [FD]: D007F80A? PageMap 0FE36000 [FD]: D007F80B? PageMap 0FE38000 [FD]: D007F80C? PageMap 0FE3A000 [FD]: D007F80D? PageMap 0FE3C000 [FD]: D007F80E? PageMap 0FE3E000 [FD]: D007F80F? PageMap 0FE40000 [FC]: D007F810? PageMap 0FE42000 [FC]: D007F811? PageMap 0FE44000 [FC]: D007F812? PageMap 0FE46000 [FC]: D007F813? PageMap 0FE48000 [FC]: D007F814? PageMap 0FE4A000 [FC]: D007F815? PageMap 0FE4C000 [FC]: D007F816? PageMap 0FE4E000 [FC]: D007F817? PageMap 0FE50000 [FC]: D007F818? PageMap 0FE52000 [FC]: D007F819? PageMap 0FE54000 [FC]: D007F81A? PageMap 0FE56000 [FC]: D007F81B? PageMap 0FE58000 [FC]: D007F81C? PageMap 0FE5A000 [FC]: D007F81D? PageMap 0FE5C000 [FC]: D007F81E? PageMap 0FE5E000 [FC]: D007F81F? # D3 = valid, writeable, not super, type 00, accessed and modified PageMap 0FE60000 [FB]: D30007FF? PageMap 0FE62000 [FB]: F0000FB1? PageMap 0FE64000 [FB]: 20000000? - invalid PageMap 0FE66000 [FB]: 20000000? - invalid PageMap 0FE68000 [FB]: 20000000? - invalid PageMap 0FE6A000 [FB]: 20000000? - invalid PageMap 0FE6C000 [FB]: 20000000? - invalid PageMap 0FE6E000 [FB]: 20000000? - invalid PageMap 0FE70000 [FB]: 20000000? - invalid PageMap 0FE72000 [FB]: 20000000? - invalid PageMap 0FE74000 [FB]: 20000000? - invalid PageMap 0FE76000 [FB]: 20000000? - invalid PageMap 0FE78000 [FB]: 20000000? - invalid PageMap 0FE7A000 [FB]: 20000000? - invalid PageMap 0FE7C000 [FB]: 20000000? - invalid PageMap 0FE7E000 [FB]: 20000000? - invalid PageMap 0FE80000 [FA]: 20000000? - invalid PageMap 0FE82000 [FA]: 20000000? - invalid PageMap 0FE84000 [FA]: 20000000? - invalid PageMap 0FE86000 [FA]: 20000000? - invalid PageMap 0FE88000 [FA]: 20000000? - invalid PageMap 0FE8A000 [FA]: 20000000? - invalid PageMap 0FE8C000 [FA]: 20000000? - invalid PageMap 0FE8E000 [FA]: 20000000? - invalid PageMap 0FE90000 [FA]: 20000000? - invalid PageMap 0FE92000 [FA]: 20000000? - invalid PageMap 0FE94000 [FA]: 20000000? - invalid PageMap 0FE96000 [FA]: 20000000? - invalid PageMap 0FE98000 [FA]: 20000000? - invalid PageMap 0FE9A000 [FA]: 20000000? - invalid PageMap 0FE9C000 [FA]: 20000000? - invalid PageMap 0FE9E000 [FA]: 20000000? - invalid # D0 = valid, writeable, not super, type 00, not accessed, not modified PageMap 0FEA0000 [F9]: D007FB00? PageMap 0FEA2000 [F9]: D007FB01? PageMap 0FEA4000 [F9]: D007FB02? PageMap 0FEA6000 [F9]: D007FB03? PageMap 0FEA8000 [F9]: D007FB04? PageMap 0FEAA000 [F9]: D007FB05? PageMap 0FEAC000 [F9]: D007FB06? PageMap 0FEAE000 [F9]: D007FB07? PageMap 0FEB0000 [F9]: D007FB08? PageMap 0FEB2000 [F9]: D007FB09? PageMap 0FEB4000 [F9]: D007FB0A? PageMap 0FEB6000 [F9]: D007FB0B? PageMap 0FEB8000 [F9]: D007FB0C? PageMap 0FEBA000 [F9]: D007FB0D? PageMap 0FEBC000 [F9]: D007FB0E? PageMap 0FEBE000 [F9]: D007FB0F? PageMap 0FEC0000 [FF]: 20000000? - invalid PageMap 0FEC2000 [FF]: 20000000? - invalid PageMap 0FEC4000 [FF]: 20000000? - invalid PageMap 0FEC6000 [FF]: 20000000? - invalid PageMap 0FEC8000 [FF]: 20000000? - invalid PageMap 0FECA000 [FF]: 20000000? - invalid PageMap 0FECC000 [FF]: 20000000? - invalid PageMap 0FECE000 [FF]: 20000000? - invalid PageMap 0FED0000 [FF]: 20000000? - invalid PageMap 0FED2000 [FF]: 20000000? - invalid PageMap 0FED4000 [FF]: 20000000? - invalid PageMap 0FED6000 [FF]: 20000000? - invalid PageMap 0FED8000 [FF]: 20000000? - invalid PageMap 0FEDA000 [FF]: 20000000? - invalid PageMap 0FEDC000 [FF]: 20000000? - invalid PageMap 0FEDE000 [FF]: 20000000? - invalid # F0 = valid, writeable, super, type 00, not accessed, not modified PageMap 0FEE0000 [F7]: F0000F70? PageMap 0FEE2000 [F7]: F0000F71? PageMap 0FEE4000 [F7]: F0000F72? PageMap 0FEE6000 [F7]: F0000F73? PageMap 0FEE8000 [F7]: F0000F74? PageMap 0FEEA000 [F7]: F0000F75? PageMap 0FEEC000 [F7]: F0000F76? PageMap 0FEEE000 [F7]: F0000F77? PageMap 0FEF0000 [F7]: D6000080? - bootrom (64K via these 8 entries) PageMap 0FEF2000 [F7]: D6000081? - bootrom PageMap 0FEF4000 [F7]: D6000082? - bootrom PageMap 0FEF6000 [F7]: D6000083? - bootrom PageMap 0FEF8000 [F7]: D4000084? - bootrom PageMap 0FEFA000 [F7]: D6000085? - bootrom PageMap 0FEFC000 [F7]: D6000086? - bootrom PageMap 0FEFE000 [F7]: D6000087? - bootrom # F0 = valid, writeable, super, type 00, not accessed, not modified # F3 = valid, writeable, super, type 00, accessed and modified PageMap 0FF00000 [F6]: F30007FD? PageMap 0FF02000 [F6]: F30007FC? PageMap 0FF04000 [F6]: F0000F62? PageMap 0FF06000 [F6]: F0000F63? PageMap 0FF08000 [F6]: F0000F64? PageMap 0FF0A000 [F6]: F0000F65? PageMap 0FF0C000 [F6]: F0000F66? PageMap 0FF0E000 [F6]: F0000F67? PageMap 0FF10000 [F6]: F0000F68? PageMap 0FF12000 [F6]: F0000F69? PageMap 0FF14000 [F6]: F0000F6A? PageMap 0FF16000 [F6]: F0000F6B? PageMap 0FF18000 [F6]: F0000F6C? PageMap 0FF1A000 [F6]: F0000F6D? PageMap 0FF1C000 [F6]: F0000F6E? PageMap 0FF1E000 [F6]: F0000F6F? PageMap 0FF20000 [F5]: F0000F50? PageMap 0FF22000 [F5]: F0000F51? PageMap 0FF24000 [F5]: F0000F52? PageMap 0FF26000 [F5]: F0000F53? PageMap 0FF28000 [F5]: F0000F54? PageMap 0FF2A000 [F5]: F0000F55? PageMap 0FF2C000 [F5]: F0000F56? PageMap 0FF2E000 [F5]: F0000F57? PageMap 0FF30000 [F5]: F0000F58? PageMap 0FF32000 [F5]: F0000F59? PageMap 0FF34000 [F5]: F0000F5A? PageMap 0FF36000 [F5]: F0000F5B? PageMap 0FF38000 [F5]: F0000F5C? PageMap 0FF3A000 [F5]: F0000F5D? PageMap 0FF3C000 [F5]: F0000F5E? PageMap 0FF3E000 [F5]: F0000F5F? PageMap 0FF40000 [F4]: F0000F40? PageMap 0FF42000 [F4]: F0000F41? PageMap 0FF44000 [F4]: F0000F42? PageMap 0FF46000 [F4]: F0000F43? PageMap 0FF48000 [F4]: F0000F44? PageMap 0FF4A000 [F4]: F0000F45? PageMap 0FF4C000 [F4]: F0000F46? PageMap 0FF4E000 [F4]: F0000F47? PageMap 0FF50000 [F4]: F0000F48? PageMap 0FF52000 [F4]: F0000F49? PageMap 0FF54000 [F4]: F0000F4A? PageMap 0FF56000 [F4]: F0000F4B? PageMap 0FF58000 [F4]: F0000F4C? PageMap 0FF5A000 [F4]: F0000F4D? PageMap 0FF5C000 [F4]: F0000F4E? PageMap 0FF5E000 [F4]: F0000F4F? PageMap 0FF60000 [F3]: F0000F30? PageMap 0FF62000 [F3]: F0000F31? PageMap 0FF64000 [F3]: F0000F32? PageMap 0FF66000 [F3]: F0000F33? PageMap 0FF68000 [F3]: F0000F34? PageMap 0FF6A000 [F3]: F0000F35? PageMap 0FF6C000 [F3]: F0000F36? PageMap 0FF6E000 [F3]: F0000F37? PageMap 0FF70000 [F3]: F0000F38? PageMap 0FF72000 [F3]: F0000F39? PageMap 0FF74000 [F3]: F0000F3A? PageMap 0FF76000 [F3]: F0000F3B? PageMap 0FF78000 [F3]: F0000F3C? PageMap 0FF7A000 [F3]: F0000F3D? PageMap 0FF7C000 [F3]: F0000F3E? PageMap 0FF7E000 [F3]: F0000F3F? PageMap 0FF80000 [FF]: 20000000? - invalid PageMap 0FF82000 [FF]: 20000000? - invalid PageMap 0FF84000 [FF]: 20000000? - invalid PageMap 0FF86000 [FF]: 20000000? - invalid PageMap 0FF88000 [FF]: 20000000? - invalid PageMap 0FF8A000 [FF]: 20000000? - invalid PageMap 0FF8C000 [FF]: 20000000? - invalid PageMap 0FF8E000 [FF]: 20000000? - invalid PageMap 0FF90000 [FF]: 20000000? - invalid PageMap 0FF92000 [FF]: 20000000? - invalid PageMap 0FF94000 [FF]: 20000000? - invalid PageMap 0FF96000 [FF]: 20000000? - invalid PageMap 0FF98000 [FF]: 20000000? - invalid PageMap 0FF9A000 [FF]: 20000000? - invalid PageMap 0FF9C000 [FF]: 20000000? - invalid PageMap 0FF9E000 [FF]: 20000000? - invalid PageMap 0FFA0000 [FF]: 20000000? - invalid PageMap 0FFA2000 [FF]: 20000000? - invalid PageMap 0FFA4000 [FF]: 20000000? - invalid PageMap 0FFA6000 [FF]: 20000000? - invalid PageMap 0FFA8000 [FF]: 20000000? - invalid PageMap 0FFAA000 [FF]: 20000000? - invalid PageMap 0FFAC000 [FF]: 20000000? - invalid PageMap 0FFAE000 [FF]: 20000000? - invalid PageMap 0FFB0000 [FF]: 20000000? - invalid PageMap 0FFB2000 [FF]: 20000000? - invalid PageMap 0FFB4000 [FF]: 20000000? - invalid PageMap 0FFB6000 [FF]: 20000000? - invalid PageMap 0FFB8000 [FF]: 20000000? - invalid PageMap 0FFBA000 [FF]: 20000000? - invalid PageMap 0FFBC000 [FF]: 20000000? - invalid PageMap 0FFBE000 [FF]: 20000000? - invalid PageMap 0FFC0000 [FF]: 20000000? - invalid PageMap 0FFC2000 [FF]: 20000000? - invalid PageMap 0FFC4000 [FF]: 20000000? - invalid PageMap 0FFC6000 [FF]: 20000000? - invalid PageMap 0FFC8000 [FF]: 20000000? - invalid PageMap 0FFCA000 [FF]: 20000000? - invalid PageMap 0FFCC000 [FF]: 20000000? - invalid PageMap 0FFCE000 [FF]: 20000000? - invalid PageMap 0FFD0000 [FF]: 20000000? - invalid PageMap 0FFD2000 [FF]: 20000000? - invalid PageMap 0FFD4000 [FF]: 20000000? - invalid PageMap 0FFD6000 [FF]: 20000000? - invalid PageMap 0FFD8000 [FF]: 20000000? - invalid PageMap 0FFDA000 [FF]: 20000000? - invalid PageMap 0FFDC000 [FF]: 20000000? - invalid PageMap 0FFDE000 [FF]: 20000000? - invalid SegMap 0FFE0000: F8? PageMap 0FFE0000 [F8]: F0000F80? PageMap 0FFE2000 [F8]: F0000F81? PageMap 0FFE4000 [F8]: F0000F82? PageMap 0FFE6000 [F8]: F0000F83? PageMap 0FFE8000 [F8]: F0000F84? PageMap 0FFEA000 [F8]: F0000F85? PageMap 0FFEC000 [F8]: F0000F86? PageMap 0FFEE000 [F8]: F0000F87? PageMap 0FFF0000 [F8]: F0000F88? PageMap 0FFF2000 [F8]: F3000F89? PageMap 0FFF4000 [F8]: F0000F8A? PageMap 0FFF6000 [F8]: F0000F8B? PageMap 0FFF8000 [F8]: F0000F8C? PageMap 0FFFA000 [F8]: F0000F8D? PageMap 0FFFC000 [F8]: F0000F8E? PageMap 0FFFE000 [F8]: D30007FE? - last 8K
Let's look closely at this last page. Consider the linear mapping for ram at the start of our address space. This mapping ends with the last page in the 8M of ram that gets set up.
The last page above is the second to last page in 16M of ram! A big surprising. This page is used by the bootrom for various purposes.
SegMap 007E0000: 3F? PageMap 007E0000 [3F]: D30003F0? PageMap 007E2000 [3F]: D30003F1? PageMap 007E4000 [3F]: D30003F2? PageMap 007E6000 [3F]: D30003F3? PageMap 007E8000 [3F]: D30003F4? PageMap 007EA000 [3F]: D30003F5? PageMap 007EC000 [3F]: D30003F6? PageMap 007EE000 [3F]: D30003F7? PageMap 007F0000 [3F]: D30003F8? PageMap 007F2000 [3F]: D30003F9? PageMap 007F4000 [3F]: D30003FA? PageMap 007F6000 [3F]: D30003FB? PageMap 007F8000 [3F]: D30003FC? PageMap 007FA000 [3F]: D30003FD? PageMap 007FC000 [3F]: D30003FE? PageMap 007FE000 [3F]: D30003FF?