[PATCH] examples: Fix vm_power_manager scratch area to /run/dpdk/powermanager

[Bruce Richardson]

On Fri, May 29, 2026 at 08:23:24AM -0700, Stephen Hemminger wrote:
> On Fri, 29 May 2026 09:01:34 +0100
> Bruce Richardson <bruce.richardson at intel.com> wrote:
> 
> > On Thu, May 28, 2026 at 07:04:48PM +0000, Sudheendra Sampath wrote:
> > > This patch for bug 1832 will do the following:
> > > 1.  If /run/dpdk is not present, it will create it first with and
> > >     then create powermanager directory underneath it.
> > > 2.  If /run/dpdk is present, it will verify it is actually a directory
> > >     before creating subdirectory, powermanager.
> > >   
> > I would suggest using $XDG_RUNTIME_DIR for the directory path, rather than
> > hardcoding it by default. If XDG_RUNTIME_DIR is not set, then maybe
> > consider using /run/dpdk. However, rather than /run/dpdk, I'd suggest using
> > the normal runtime dir path on most distros as the default:
> > /run/user/<uid>.
> > 
> > /Bruce
> 
> The login in EAL is a little more detailed.
> The choice is from systemd conventions which follows filesystem hierarchy.
> 
> 
> int eal_create_runtime_dir(void)
> {
> 	const char *directory;
> 	char run_dir[PATH_MAX];
> 	char tmp[PATH_MAX];
> 	int ret;
> 
> 	/* from RuntimeDirectory= see systemd.exec */
> 	directory = getenv("RUNTIME_DIRECTORY");
> 	if (directory == NULL) {
> 		/*
> 		 * Used standard convention defined in
> 		 * XDG Base Directory Specification and
> 		 * Filesystem Hierarchy Standard.
> 		 */
> 		if (getuid() == 0)
> 			directory = "/var/run";
> 		else
> 			directory = getenv("XDG_RUNTIME_DIR") ? : "/tmp";
> 	}
> 
> 	/* create DPDK subdirectory under runtime dir */
> 	ret = snprintf(tmp, sizeof(tmp), "%s/dpdk", directory);
> 	if (ret < 0 || ret == sizeof(tmp)) {
> 		EAL_LOG(ERR, "Error creating DPDK runtime path name");
> 		return -1;
> 	}
> 
> 	/* create prefix-specific subdirectory under DPDK runtime dir */
> 	ret = snprintf(run_dir, sizeof(run_dir), "%s/%s",
> 			tmp, eal_get_hugefile_prefix());
> 	if (ret < 0 || ret == sizeof(run_dir)) {
> 		EAL_LOG(ERR, "Error creating prefix-specific runtime path name");
> 		return -1;
> 	}
> 
> 	/* create the path if it doesn't exist. no "mkdir -p" here, so do it
> 	 * step by step.
> 	 */
> 	ret = mkdir(tmp, 0700);
> 	if (ret < 0 && errno != EEXIST) {
> 		EAL_LOG(ERR, "Error creating '%s': %s",
> 			tmp, strerror(errno));
> 		return -1;
> 	}
> 
> 	ret = mkdir(run_dir, 0700);
> 	if (ret < 0 && errno != EEXIST) {
> 		EAL_LOG(ERR, "Error creating '%s': %s",
> 			run_dir, strerror(errno));
> 		return -1;
> 	}

Yes. Can the power manager call the rte_eal_get_runtime_dir() API and use
that as a basis for its working directory? Save duplicating all this logic.

/Bruce