1 /* 2 * xtos-params.h -- user-settable parameters for XTOS single-threaded run-time 3 * 4 * Copyright (c) 2002, 2004, 2006-2007 Tensilica Inc. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining 7 * a copy of this software and associated documentation files (the 8 * "Software"), to deal in the Software without restriction, including 9 * without limitation the rights to use, copy, modify, merge, publish, 10 * distribute, sublicense, and/or sell copies of the Software, and to 11 * permit persons to whom the Software is furnished to do so, subject to 12 * the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included 15 * in all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 18 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 20 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 21 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 22 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 23 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 24 */ 25 26 #ifndef XTOS_PARAMS_H 27 #define XTOS_PARAMS_H 28 29 /* 30 * IMPORTANT NOTE. 31 * This file contains XTOS parameters that may be modified 32 * according to needs. HOWEVER, any modifications are NOT 33 * supported. Handling of parameters other than the defaults 34 * provided in the original version of this file are for 35 * illustrative and educational purposes only. If you do 36 * change the parameters here-in (which requires rebuilding 37 * XTOS), please verify the resulting code extensively 38 * before even considering its use in production code. 39 * 40 * To rebuild XTOS, see instructions in the Xtensa System Software 41 * Reference Manual. The following sequence is no longer supported. 42 * 43 * cd <config_dir>/xtensa-elf/src/handlers 44 * xt-make clean 45 * xt-make 46 * xt-make install 47 * 48 * (Note: the last step installs the modified XTOS in *ALL* 49 * LSPs that normally include XTOS. You may prefer copying 50 * the generated files to your own custom LSP instead. Or 51 * better yet, also make a copy of all source files and maintain 52 * them somewhere completely separate -- which may require 53 * minor adjustments to the makefile.) 54 * 55 * PERFORMANCE TUNING: 56 * To slightly improve performance of interrupt dispatching, 57 * you can do some combination of the following: 58 * - change XTOS_SUBPRI to zero 59 * - change XTOS_SUBPRI_GROUPS to zero 60 * - change XTOS_SUBPRI_ORDER to XTOS_SPO_ZERO_HI 61 * - change XTOS_DEBUG_PC to zero 62 * - change XTOS_INT_FAIRNESS to zero 63 * - change XTOS_CNEST to zero 64 * There are non-trivial trade-offs in making such changes however, 65 * such as loss of support (see important note above), loss of 66 * interrupt scheduling fairness, loss of ability to traceback 67 * interrupt handlers across interrupted code when debugging them, 68 * loss of supported for nested C functions, etc. 69 */ 70 71 72 /* 73 * Lower LOCKLEVEL to XCHAL_EXCM_LEVEL for improved interrupt latency 74 * if you don't register C handlers for high-priority interrupts and your 75 * high-priority handlers don't touch INTENABLE nor virtual priorities. 76 * 77 * XTOS_LOCKLEVEL is less meaningful but still relevant if XEA2 and SUBPRI is zero, 78 * ie. if INTENABLE doesn't get virtualized (XTOS_VIRTUAL_INTENABLE not set); 79 * in this case, it is the interrupt level at which INTENABLE accesses are guarded, 80 * so that interrupt handlers up to this level can safely manipulate INTENABLE. 81 */ 82 #define XTOS_LOCKLEVEL XCHAL_NUM_INTLEVELS /* intlevel of INTENABLE register virtualization 83 (minimum is EXCM_LEVEL) */ 84 85 /* 86 * NOTE: the following four parameters (SUBPRI, SUBPRI_GROUPS, SUBPRI_ORDER, INT_FAIRNESS) 87 * are irrelevant and ignored for interrupt vectors to which only one interrupt is mapped. 88 */ 89 90 #define XTOS_SUBPRI 1 /* set to 0 if you don't need sub-prioritization 91 within level-one interrupts via software; 92 for XEA2 configs, this might improve performance of 93 certain sections of code, because INTENABLE register 94 virtualization becomes unnecessary in this case */ 95 96 /* Ignored unless SUBPRI set: */ 97 #define XTOS_SUBPRI_GROUPS 1 /* 1 = support selective grouping of interrupts at the same priority */ 98 99 #define XTOS_SUBPRI_ORDER XTOS_SPO_ZERO_LO /* one of XTOS_SPO_ZERO_LO, XTOS_SPO_ZERO_HI */ 100 101 /* Ignored if SUBPRI set but SUBPRI_GROUPS is not (single interrupt per subpri), 102 * or if single interrupt configured at level/vector: */ 103 #define XTOS_INT_FAIRNESS 1 /* 1 = enable round-robin/fifo scheduling of interrupt 104 handlers of a given level or sub-priority */ 105 106 107 #define XTOS_DEBUG_PC 1 /* 1 = enable nice stack traceback showing interrupted code 108 when debugging interrupt or exception handler; 109 not implemented for high-priority handlers, or 110 for call0 ABI */ 111 112 #define XTOS_CNEST 1 /* 1 = enable support for nested C functions 113 (save/restore nested C function call-chain pointer) */ 114 115 /* Current compilers only use ACC (not MRn) when MAC16 is enabled, so you can leave this 0 for performance: */ 116 #define XTOS_SAVE_ALL_MAC16 0 /* set to save/restore MAC16 MRn registers */ 117 118 /* Setting this might be useful to clear X's in hardware simulation a bit earlier, but 119 * should not be needed in production code: */ 120 #define XTOS_RESET_UNNEEDED 0 /* set to reset more registers than are really needed */ 121 122 #endif /* XTOS_PARAMS_H */ 123 124
