Title: Kernel Footprint Measurement
Description:
This project is designed to characterize the memory requirements of a
standard kernel image running on an Atom target.
The project can be built using several configurations:
minimal (a "do nothing" image that has support for few kernel capabilities)
-------
- Idle task is only task in system.
- No system timer support.
- ISR for the spurious interrupt handling is present.
- IDT and stack memory sizes are very limited.
- Provides support for 2 task priorities.
regular (a "typical" image that has support for some kernel capabilities)
-------
- As for "minimal" configuration, except as noted below.
- Supports larger IDT and utilizes larger stacks.
- A statically linked dummy ISR is present.
- Has "foreground" task that prints a message to the console via printk().
- Provides support for 16 task priorities.
- Supports system timer, along with task scheduler support for time slicing.
- Links in support for EVENT, MUTEX, FIFO, and MAP objects.
maximal (a "complex" image that has support for many kernel capabilities)
-------
- As for "regular" configuration, except as noted below.
- Supports full IDT and utilizes even larger stacks.
- Provides support for 64 task priorities.
- Foreground task dynamically links in the dummy ISR, rather than having
it statically linked.
- Foreground task prints a message to the console via printf(),
rather than printk().
- Links in support for SEMAPHORE, PIPE, MAILBOX, and POOL objects.
- Links in support for task device interrupt handling and additional task APIs.
- Adds advanced power management support (including tickless idle).
- Adds floating point support (for x87 FPU, including SSE).
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Building and Running Project:
This project does not generate any output in the default case
(TEST=min). In the regular case (TEST=reg) and the maximal case (TEST=max),
it outputs to the console. It can be built and executed on QEMU as follows:
make TEST=min qemu (minimal configuration)
make TEST=reg qemu (regular configuration)
make TEST=max qemu (maximal configuration)
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Troubleshooting:
Problems caused by out-dated project information can be addressed by
issuing one of the following commands then rebuilding the project:
make clean # discard results of previous builds
# but keep existing configuration info
or
make pristine # discard results of previous builds
# and restore pre-defined configuration info
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Sample Output:
The resulting image is bootable for all configurations, but produces different
output in each case.
minimal
-------
This configuration does NOT produce any output. To observe its operation,
invoke it using gdb and observe that:
- the kernel's timer ISR & main thread increment "K_LowTime" on a regular
basis
- nano_cpu_idle() is invoked by the idle task each time K_LowTime is incremented
regular
-------
This configuration prints the following message to the console:
Running regular kernel configuration
maximal
-------
This configuration prints the following message to the console:
Running maximal kernel configuration
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Additional notes:
Various host utilities (such as the Unix "size" utility) can be used
to determine the footprint of the resulting
outdir/$BOARD/zephyr.elf image.
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