IBM PowerPC 750GX

User’s Manual
IBM PowerPC 750GX and 750GL RISC Microprocessor
Page 10 of 377
750gx_umTOC.fm.(1.2)
March 27, 2006
8.6.2 No-DRTRY Mode ................................................................................................................. 318
8.7 Processor State Signals ................................................................................................................ 319
8.7.1 Support for the lwarx and stwcx. Instruction Pair ............................................................... 319
8.7.2 TLBISYNC
Input .................................................................................................................. 319
8.8 IEEE 1149.1a-1993 Compliant Interface ....................................................................................... 319
8.8.1 JTAG/COP Interface ............................................................................................................ 319
8.9 Using Data-Bus Write-Only ........................................................................................................... 320
9. L2 Cache ................................................................................................................... 323
9.1 L2 Cache Overview ....................................................................................................................... 323
9.2 L2 Cache Operation ...................................................................................................................... 323
9.3 L2 Cache Control Register (L2CR) ............................................................................................... 329
9.4 L2 Cache Initialization ................................................................................................................... 329
9.5 L2 Cache Global Invalidation ........................................................................................................ 329
9.6 L2 Cache Used as On-Chip Memory ............................................................................................ 330
9.6.1 Locking the L2 Cache .......................................................................................................... 330
9.6.1.1 Loading the Locked L2 Cache ...................................................................................... 331
9.6.1.2 Locked Cache Operation .............................................................................................. 331
9.7 Data-Only and Instruction-Only Modes ......................................................................................... 332
9.8 L2 Cache Test Features and Methods .......................................................................................... 332
9.8.1 L2CR Support for L2 Cache Testing .................................................................................... 332
9.8.2 L2 Cache Testing ................................................................................................................. 333
9.9 L2 Cache Timing ........................................................................................................................... 333
10. Power and Thermal Management ........................................................................ 335
10.1 Dynamic Power Management ..................................................................................................... 335
10.2 Programmable Power Modes ...................................................................................................... 335
10.2.1 Power Management Modes ............................................................................................... 337
10.2.1.1 Full On Mode .............................................................................................................. 337
10.2.1.2 Doze Mode ................................................................................................................. 337
10.2.1.3 Nap Mode ................................................................................................................... 337
10.2.1.4 Sleep Mode ................................................................................................................ 339
10.2.1.5 Dynamic Power Reduction ......................................................................................... 339
10.2.2 Power Management Software Considerations ................................................................... 340
10.3 750GX Dual PLL Feature ............................................................................................................ 340
10.3.1 Overview ............................................................................................................................ 340
10.3.2 Configuration Restriction on Frequency Transitions .......................................................... 341
10.3.3 Dual PLL Implementation ................................................................................................... 342
10.4 Thermal Assist Unit ..................................................................................................................... 343
10.4.1 Thermal Assist Unit Overview ............................................................................................ 343
10.4.2 Thermal Assist Unit Operation ........................................................................................... 344
10.4.2.1 TAU Single-Threshold Mode ...................................................................................... 345
10.4.2.2 TAU Dual-Threshold Mode ......................................................................................... 346
10.4.2.3 750GX Junction Temperature Determination ............................................................. 346
10.4.2.4 Power Saving Modes and TAU Operation .................................................................. 347
10.5 Instruction-Cache Throttling ........................................................................................................ 347
11. Performance Monitor and System Related Features ......................................... 349