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

[Stephen Hemminger]

On Fri, 29 May 2026 09:01:34 +0100
Bruce Richardson <bruce.richard...@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;
        }