feat: add host-backed entropy device support and update kernel configuration

uvm/config.py

@@ -10,7 +10,9 @@ from pathlib import Path
 from .errors import ConfigurationError
 
 
-DEFAULT_GUEST_ASSETS_URL = "https://s3.amazonaws.com/spec.ccfc.min/img/quickstart_guide"
+# Pin published kernels with built-in virtio-rng support. The artifact series
+# is independent of the VMM release; the old ARM quickstart kernel lacks this driver.
+DEFAULT_GUEST_ASSETS_URL = "https://s3.amazonaws.com/spec.ccfc.min/firecracker-ci/v1.15"
 MIN_STORAGE_MIB = 30 * 1024
 MAX_STORAGE_MIB = (2**63 - 1) // (1024 * 1024)
 
@@ -55,7 +57,7 @@ class Settings:
         # Resolve defaults at construction time, while preserving individual URL overrides.
         asset_base = f"{DEFAULT_GUEST_ASSETS_URL}/{architecture}"
         if not self.kernel_url:
-            object.__setattr__(self, "kernel_url", f"{asset_base}/kernels/vmlinux.bin")
+            object.__setattr__(self, "kernel_url", f"{asset_base}/vmlinux-6.1.155")
 
         if self.gateway not in self.network:
             raise ConfigurationError(