Drupal's PHP demo not working without preopen root directory

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Describe the bug

A WasmMapDir / / directive seems needed in mod_wasm Drupal's demo and other PHP demos.

Apparently, the PHP runtime performs some checks during the bootup that require access to the root directory. When removing this permission, PHP doesn't boot up as expected.

Reproduction steps

Run mod_wasm's Drupal demo, and remove the line WasmMapDir / /, restart Apache and try again.

Expected behavior

PHP should be able to boot up even if the root directory is not pre-open.

Additional context

No response