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