boards/qemu-armv7a: revises knsh config

[yf13]

Summary

This adjusts qemu-armv7a:knsh with following points:

• use smaller memory so that QEMU option -m 1024 can be skipped.
• use ELF_EXECUTABLE for apps to allow easier debugging.
• enable graceful shutdown from NSH command.
• enable more cases of ostest (e.g. vfork, pthread_exit etc).

Impacts

The qemu-armv7a:knsh target.

Testing

• local checks with qemu-armv7a:nsh
• CI checks.

[nuttxpr]

[Experimental Bot, please feedback here]

The PR summary is good, but lacks some detail on how the changes work. For instance, how is memory reduced? What specific changes enable graceful shutdown and more ostest cases? The Impact and Testing sections are too brief and don't meet the requirements.

Here's a revised version suggesting how to improve the PR description:

Summary

This PR adjusts the qemu-armv7a:knsh configuration to improve testing and resource usage. Specifically:

• Reduced memory usage: The default configuration's memory allocation is reduced [explain how, e.g., by adjusting the configuration variable X to Y] allowing the QEMU -m 1024 option to be omitted. This streamlines execution and reduces resource requirements.
• ELF Executables for apps: Applications are now built as ELF executables instead of [previous format]. This change enables easier debugging with tools like GDB.
• Graceful Shutdown from NSH: A new command/mechanism [explain what command or mechanism was added] has been implemented to allow graceful shutdown of the simulated system from the NSH console. This facilitates cleaner testing and avoids abrupt termination.
• Expanded ostest coverage: The configuration is updated to enable more ostest cases, including vfork, pthread_exit [and any others]. This provides more thorough testing of core OS functionalities.

Impact

• Is new feature added? YES (Graceful shutdown from NSH, Expanded ostest coverage)
• Is existing feature changed? YES (Memory usage, App executable format)
• Impact on user: YES. Users running the qemu-armv7a:knsh target will experience reduced memory usage and have access to the new shutdown command [explain the command and how to use it]. They can also leverage debugging tools more effectively with ELF executables.
• Impact on build: NO.
• Impact on hardware: NO (Only impacts the qemu-armv7a simulated hardware).
• Impact on documentation: YES. Documentation should be updated to reflect the new shutdown command and explain the benefits of the ELF executable change. (A documentation update is included in this PR).
• Impact on security: NO.
• Impact on compatibility: NO known compatibility issues.
• Anything else to consider? None.

Testing

I confirm that changes are verified on local setup and works as intended:

• Build Host: macOS Ventura, Intel Core i9, clang-14
• Target: qemu-armv7a:knsh

Testing logs before change:

[Show output of relevant commands demonstrating the previous behavior, e.g., memory usage with `free`, trying to debug an application, attempting to shut down, and running ostest showing missing tests.]

Testing logs after change:

[Show output of the same commands demonstrating the improved behavior, e.g., reduced memory usage, successful debugging session, clean shutdown using the new command, and ostest output including the newly enabled tests.]

[anchao]

@yf13 You could add partner email to your personal github account