KThreadContext: Difference between revisions
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! Type | ! Type | ||
! Description | ! Description | ||
|- | |||
| 0xF38 | |||
| u32[4] | |||
| SVC access control data copied from KThread's owner process | |||
|- | |- | ||
| 0xF50 | | 0xF50 | ||
| Line 25: | Line 29: | ||
* Load r4-r11, SP, LR | * Load r4-r11, SP, LR | ||
* Branch back to r1, preserving the LR which was just reloaded, back to the main scheduling function, but in the context of the newly switched-to thread | * Branch back to r1, preserving the LR which was just reloaded, back to the main scheduling function, but in the context of the newly switched-to thread | ||
* Disable Interrupts | |||
* Check if that core's KScheduler object indicates that it needs switching again and exit if it does not | |||
* Otherwise, run the thread scheduler again and repeat all the steps to switch contexts again | |||
Revision as of 01:11, 29 August 2016
Size : 0x1000 bytes (1 page)
| Offset | Type | Description |
|---|---|---|
| 0xF38 | u32[4] | SVC access control data copied from KThread's owner process |
| 0xF50 | u32[10] | SVC mode registers, r4-r11, r13, r14 |
| 0xFF8 | u32 | FPEXC, floating point exception register for thread- stored and loaded on context switches |
When switching thread contexts the kernel does, in order:
- Load FPEXC
- Save the LR to r1- this LR is the return back to the main scheduling and context switching function
- Load r4-r11, SP, LR
- Branch back to r1, preserving the LR which was just reloaded, back to the main scheduling function, but in the context of the newly switched-to thread
- Disable Interrupts
- Check if that core's KScheduler object indicates that it needs switching again and exit if it does not
- Otherwise, run the thread scheduler again and repeat all the steps to switch contexts again