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Sebastian Huber
ea80e1d7ba
The exception path of _ISR_Handler() read the control and status register of coprocessor 1 with mfc1 and wrote it back with mtc1. Those instructions address a floating point data register. cfc1 and ctc1 address a control register. So the save put the bits of $f31 into the frame at R_FCSR, over the value which the prologue stored there. The restore put the slot into $f31 and destroyed that register. The same pair used C1_REVISION, which is $f0 and which holds the identity of the unit rather than state of a context. Drop both accesses. The prologue stores the register through the two-read idiom of the port and the exit restores it with ctc1, so the exception path needs neither. Nothing fills R_FEIR, because no MIPS32 processor carries that register. Update #5769. Assisted-by: Claude:claude-opus-5 claude-code Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Real-Time Executive for Multiprocessing Systems
RTEMS is a real-time executive (kernel) which provides a high performance environment for embedded applications with the following features:
- Standards based user interfaces.
- Multitasking capabilities.
- Homogeneous and heterogeneous multiprocessor systems.
- Symmetric Multiprocessing (SMP):
- Cluster scheduling: Job-level fixed prority scheduler (EDF) with support for one-to-one and one-to-all thread to processor affinities.
- Locking protocols with transitive priority inheritance, priority ceiling, MRsP and OMIP.
- Event-driven, priority-based, preemptive scheduling.
- Scalable timer and timeout support.
- Optional rate monotonic scheduling.
- Intertask communication and synchronisation.
- Priority inheritance.
- Responsive interrupt management.
- Dynamic memory allocation.
- Dynamic code loading using run-time link editing.
- File systems, IMFS, FAT, RFS, JFFS, NSFv4 (with LibBSD)
- High level of user configurability.
- Link-time configurable schedulers.
- Linker-set based initialization (similar to global C++ constructors).
- Drivers for I2C, SPI and LibBSD has NIC, USB, SD/MMC and Framebuffer.
- Open source with a friendly user license.
RTEMS Project:
Project git repositories are located at:
Online documentation is available at:
RTEMS Doxygen for CPUKit:
RTEMS POSIX 1003.1 Compliance Guide:
RTEMS Discourse User forum for questions, answers and examples:
RTEMS Discord for support:
RTEMS Mailing Lists for general purpose use the users list and for developers use the devel list.
The version number for this software in releases is located in the VERSION file if present.