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Line 103:
Line 103:
There are 4 KResourceLimit objects created on the kernel heap. Each is used for a different category specified by the exheader's resource limit category specifier in the exheader [[NCCH/Extended_Header#ARM11_Local_System_Capabilities|ARM11 Local System Capabilities]].+
+
+
|-
|-
| 0x60
| 0x60
+| KPreemptionTimer
+| Preemption timer for the current core, see below
+|}
+
+There are 4 KResourceLimit objects created on the kernel heap. Each is used for a different category specified by the exheader's resource limit category specifier in the exheader [[NCCH/Extended_Header#ARM11_Local_System_Capabilities|ARM11 Local System Capabilities]].
+
+'''KPreemptionTimer''':
+
+{| class="wikitable" border="1"
+|-
+! Offset
+! Type
+! Description
+|-
+| 0x0
| u32
| u32
−| CPU time available in ticks
+| Max CPU time in ticks for preemption type 0 (default preemption type)
|-
|-
−| 0x64
+| 0x4
| u32
| u32
−| Unknown
+| Current timer (in watchdog timer ticks)
|-
|-
−| 0x68
+| 0x8
| u32
| u32
−| Unknown
+| Last remembered watchdog timer counter value
|-
|-
−| 0x6C
+| 0xC
−| u32
+| u32
−| Unknown
+| Max CPU time in ticks for preemption type 1
|}
|}
+A call to svcSetResourceLimitValues with a limit value of 1000 for CPU time must be done first to set up some global variables and the associated [[KTimeableInterruptEvent]] instances, and another call needs to be made to actually enable preemption.
−Preemption type 0: this is the default, preempts threads on core1 and allow them to run only 2ms * (timeLimit / 100).
+Preemption type 1: ''seems'' to be borked, it was apparently intended to preempt threads on all cores but seems to only preempt the kernel thread running the preemptor itself and threads on core1... (time slice: 12.5ms * (timeLimit / 100))
+"Firm" dev consoles can switch between these two types using svcKernelSetState type 6.