modify DEV_ZERO config on Nuttx's built-in board

[luckyyaojin]

Note: Please adhere to Contributing Guidelines.

Summary

*/dev/zero is a very commonly used config, for example use
/dev/zero to test the filesystem, mtd or block devices performance.
So let's default enable it when not enable DEFAULT_SMALL

Impact

Nuttx's built-in boards' defconfig

Testing

CI

[nuttxpr]

[Experimental Bot, please feedback here]

No, this PR summary does not adequately meet the NuttX requirements. Here's why and how to fix it:

Missing Information in Summary:

• Why is the change necessary? The summary mentions a common use case, but doesn't explain why it should be default enabled. Is it frequently requested? Does it solve a specific problem? Justify the change beyond just its utility. For example: "Enabling /dev/zero by default simplifies performance testing and reduces configuration overhead for users, as it's a commonly used device."
• What functional part of the code is being changed? Vague reference to "Nuttx's built-in boards' defconfig". Be specific. Which files are modified? Is this a Kconfig change? Which subsystem is affected (Device drivers, core OS, etc.)? For example: "This change modifies the default configuration in the Kconfig files for various boards to enable the /dev/zero device driver when DEFAULT_SMALL is not enabled."
• How does the change exactly work? While it states what will change (default enable), it doesn't describe how. Does it involve a Kconfig option modification? Is any code added or removed? For example: "The CONFIG_DEV_ZERO option is set to 'y' in the relevant defconfig files when CONFIG_DEFAULT_SMALL is not selected."

Missing Information in Impact:

• All impact sections are answered too briefly or with placeholders. Be explicit.
  • Is new feature added? Is existing feature changed? "Yes, existing feature changed. The /dev/zero device driver, which was previously disabled by default (unless DEFAULT_SMALL was used), is now enabled by default."
  • Impact on user: Even if the answer is NO, explain why. "No, users will not need to adapt. The /dev/zero device will be available without any explicit configuration, simplifying common use cases." If a user might have to adapt (e.g., size changes), document that!
  • Impact on build: "Potentially YES. The resulting kernel image might be slightly larger due to the inclusion of the /dev/zero driver. This impact is expected to be minimal."
  • Impact on hardware: "NO. This change affects only the kernel configuration and does not introduce any new hardware dependencies."
  • Impact on documentation: If NO, confirm: "NO, documentation updates are not required as this is a default configuration change." If YES, describe what documentation is changed.
  • Impact on security: "NO, this change has no security implications. The /dev/zero device has a well-defined and limited functionality."
  • Impact on compatibility: "NO, this change does not affect backward or forward compatibility."

Missing Information in Testing:

• Build Host(s): Provide details: "Linux (Ubuntu 20.04), x86_64, GCC 9.4.0"
• Target(s): Be specific! "qemu-x86_64:nsh_net", "sim:nsh", "stm32f4discovery:nsh" List all tested targets.
• Testing logs: Absolutely essential. Show commands used and relevant output before and after the change to demonstrate that the /dev/zero device is now available and functions correctly. Example:

Before:
$ ls /dev | grep zero
# No output

After:
$ ls /dev | grep zero
zero

$ dd if=/dev/zero of=/tmp/test bs=1k count=10
10+0 records in
10+0 records out
10240 bytes (10 kB) copied, 0.000180119 s, 56.8 MB/s

By providing this level of detail, reviewers can properly assess the PR and ensure it meets the project's standards. Conciseness is good, but not at the expense of clarity and completeness.

[acassis]

@luckyyaojin /dev/null also should be enabled by default, it is very useful as /dev/zero

[xiaoxiang781216]

@luckyyaojin /dev/null also should be enabled by default, it is very useful as /dev/zero

let's create a new patch for this, @luckyyaojin

[luckyyaojin]

@luckyyaojin /dev/null also should be enabled by default, it is very useful as /dev/zero

let's create a new patch for this, @luckyyaojin

@xiaoxiang781216 @acassis /dev/null is already enabled by default

[hartmannathan]

The CI error is in esp32c3-devkit/knsh config:

Configuration/Tool: esp32c3-devkit/knsh
2024-12-22 09:31:23
------------------------------------------------------------------------------------
  Cleaning...
  Configuring...
  Building NuttX...
Error: ./chip/esp32c3_region.c:44:4: error: #error "ESP32C3_REGION_PROTECTION shall not be enabled with Protected Mode"
   44 | #  error "ESP32C3_REGION_PROTECTION shall not be enabled with Protected Mode"
      |    ^~~~~
ERROR: riscv-none-elf-gcc failed: 1

Any ideas?