This is just a proof of concept utility that takes a PCI device address
and a monitor ID and finds the xrandr output associated with that
monitor id. It assumes that the list of drm connectors (outputs) are
in a stable order and therefore we can use the monitor ID as an index
into the array of connectors.
---
This isn't intended to be committed to the repository, but it gives an
example for how we might do this. This will be necessary to handle vgpu
streaming functionality properly.
To test, you can simply run the utility and pass a PCI address and
monitor ID and it should print out the associated Xrandr output id. For
example, on my laptop:
$ ./src/get-xrandr-output 0000:00:02.0 0
Device /dev/dri/card0 is at ../../../0000:00:02.0
DRM connector for monitor 0: name=eDP-1 id=71 (*CONNECTED*)
Found matching X Output: name=eDP-1 id=114 (*CONNECTED*)
Makefile.am | 16 +++
configure.ac | 1 +
src/vdagent/get-xrandr-output.c | 209 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 226 insertions(+)
create mode 100644 src/vdagent/get-xrandr-output.c
diff --git a/Makefile.am b/Makefile.am
index 3e405bc..cdadb87 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,6 +3,7 @@ NULL =
bin_PROGRAMS = src/spice-vdagent
sbin_PROGRAMS = src/spice-vdagentd
+noinst_PROGRAMS = src/get-xrandr-output
common_sources = \
src/udscs.c \
@@ -77,6 +78,21 @@ src_spice_vdagentd_SOURCES = \
src/vdagentd/virtio-port.h \
$(NULL)
+src_get_xrandr_output_SOURCES = \
+ src/vdagent/get-xrandr-output.c \
+ $(NULL)
+
+src_get_xrandr_output_CFLAGS = \
+ $(AM_CPPFLAGS) \
+ $(DRM_CFLAGS) \
+ $(X_CFLAGS) \
+ $(NULL)
+
+src_get_xrandr_output_LDADD = \
+ $(DRM_LIBS) \
+ $(X_LIBS) \
+ $(NULL)
+
if HAVE_CONSOLE_KIT
src_spice_vdagentd_SOURCES += src/vdagentd/console-kit.c
else
diff --git a/configure.ac b/configure.ac
index 7cb44db..55b031e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -105,6 +105,7 @@ PKG_CHECK_MODULES(X, [xfixes xrandr >= 1.3 xinerama x11])
PKG_CHECK_MODULES(SPICE, [spice-protocol >= 0.12.13])
PKG_CHECK_MODULES(ALSA, [alsa >= 1.0.22])
PKG_CHECK_MODULES([DBUS], [dbus-1])
+PKG_CHECK_MODULES([DRM], [libdrm])
if test "$with_session_info" = "auto" || test "$with_session_info" = "systemd"; then
PKG_CHECK_MODULES([LIBSYSTEMD_LOGIN],
diff --git a/src/vdagent/get-xrandr-output.c b/src/vdagent/get-xrandr-output.c
new file mode 100644
index 0000000..2127e66
--- /dev/null
+++ b/src/vdagent/get-xrandr-output.c
@@ -0,0 +1,209 @@
+/* proof of concept for converting PCI address and monitor id to an xrandr
+ * output in the guest.
+ *
+ * \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include <unistd.h>
+#include <X11/extensions/Xrandr.h>
+
+#define ERROR(...) \
+ fprintf(stderr, __VA_ARGS__); \
+ return EXIT_FAILURE;
+
+// connector type strings from kernel /drivers/gpu/drm/drm_connector.c
+// these *should* match the drm Xrandr output names
+static const char *conn_type[] = {
+ [ DRM_MODE_CONNECTOR_Unknown] = "Unknown" ,
+ [ DRM_MODE_CONNECTOR_VGA] = "VGA" ,
+ [ DRM_MODE_CONNECTOR_DVII] = "DVI-I" ,
+ [ DRM_MODE_CONNECTOR_DVID] = "DVI-D" ,
+ [ DRM_MODE_CONNECTOR_DVIA] = "DVI-A" ,
+ [ DRM_MODE_CONNECTOR_Composite] = "Composite" ,
+ [ DRM_MODE_CONNECTOR_SVIDEO] = "SVIDEO" ,
+ [ DRM_MODE_CONNECTOR_LVDS] = "LVDS" ,
+ [ DRM_MODE_CONNECTOR_Component] = "Component" ,
+ [ DRM_MODE_CONNECTOR_9PinDIN] = "DIN" ,
+ [ DRM_MODE_CONNECTOR_DisplayPort] = "DP" ,
+ [ DRM_MODE_CONNECTOR_HDMIA] = "HDMI-A" ,
+ [ DRM_MODE_CONNECTOR_HDMIB] = "HDMI-B" ,
+ [ DRM_MODE_CONNECTOR_TV] = "TV" ,
+ [ DRM_MODE_CONNECTOR_eDP] = "eDP" ,
+ [ DRM_MODE_CONNECTOR_VIRTUAL] = "Virtual" ,
+ [ DRM_MODE_CONNECTOR_DSI] = "DSI" ,
+ [ DRM_MODE_CONNECTOR_DPI] = "DPI" ,
+};
+
+// FIXME: LICENSE?
+// borrowed from Gerd's drminfo
+void drm_conn_name(drmModeConnector *conn, char *dest, int dlen)
+{
+ const char *type;
+
+ if (conn->connector_type_id < sizeof(conn_type)/sizeof(conn_type[0]) &&
+ conn_type[conn->connector_type]) {
+ type = conn_type[conn->connector_type];
+ } else {
+ type = "unknown";
+ }
+ snprintf(dest, dlen, "%s-%d", type, conn->connector_type_id);
+}
+
+static const char *connections[] = {"", "*CONNECTED*", "disconnected", "unknown connection"};
+
+int main(int argc, char* argv[])
+{
+ if (argc < 3) {
+ ERROR("Usage: %s PCIADDR MONITORID", argv[0]);
+ }
+
+ // PCI address should be in extended BDF notation
+ // https://wiki.xen.org/wiki/Bus:Device.Function_(BDF)_Notation
+ // FIXME: validate?
+ char* user_addr = argv[1];
+ int monitor_id = atoi(argv[2]);
+
+ bool found = false;
+ for (int i = 0; i < 10; ++i) {
+ char dev_path[64];
+ struct stat buf;
+
+ // device node for the card is needed to access libdrm functionality
+ snprintf(dev_path, sizeof(dev_path), DRM_DEV_NAME, DRM_DIR_NAME, i);
+ if (stat(dev_path, &buf) != 0) {
+ // no card exists, exit loop
+ break;
+ }
+
+ // the sysfs directory for the card will allow us to determine the
+ // pci address for the device
+ char sys_path[64];
+ snprintf(sys_path, sizeof(sys_path), "/sys/class/drm/card%d", i);
+
+ // the file /sys/class/drm/card0/device is a symlink to a file that
+ // specifies the device's address. It usually points to something
+ // like ../../../0000:00:02.0
+ char sys_path_device[100], device_link[100];
+ snprintf(sys_path_device, sizeof(sys_path_device), "%s/device", sys_path);
+ ssize_t res = readlink(sys_path_device, device_link, sizeof(device_link) - 1);
+ if (res == -1) {
+ ERROR(strerror(errno));
+ }
+ // readlink does not guarantee that the string is null-terminated
+ device_link[res] = '\0';
+ printf("Device %s is at %s\n", dev_path, device_link);
+
+ char *card_addr = device_link;
+ // strip possible initial relative path
+ char *delim = strrchr(device_link, '/');
+ if (delim != NULL) {
+ card_addr = delim + 1;
+ }
+
+ if (strcmp(card_addr, user_addr) == 0) {
+ int fd;
+ fd = open(dev_path, O_RDWR);
+ if (fd < 0) {
+ ERROR(strerror(errno));
+ }
+
+ drmModeResPtr res = drmModeGetResources(fd);
+ if (!res) {
+ ERROR("Unable to get resources for card");
+ }
+
+ // find the drm output that is equal to monitor_id
+ /* FIXME: verify that monitor id is 0-based */
+ if (res->count_connectors < (monitor_id + 1)) {
+ ERROR("Unable to find output");
+ }
+
+ drmModeConnectorPtr conn = drmModeGetConnector(fd, res->connectors[monitor_id]);
+ char cname[64];
+ drm_conn_name(conn, cname, sizeof(cname));
+ printf("DRM connector for monitor %i: name=%s id=%u (%s)\n",
+ monitor_id, cname, conn->connector_id,
+ connections[conn->connection]);
+
+ drmModeFreeConnector(conn);
+ conn = NULL;
+ drmModeFreeResources(res);
+ res = NULL;
+
+ // now look up all xrandr outputs
+ Display *xdisplay = XOpenDisplay(NULL);
+ if (!xdisplay) {
+ ERROR("Failed to open X dislay");
+ }
+
+ int rr_event_base, rr_error_base;
+ if (!XRRQueryExtension(xdisplay, &rr_event_base, &rr_error_base)) {
+ ERROR("Failed to initialize XRandr extension");
+ }
+
+ XRRScreenResources *xres = XRRGetScreenResourcesCurrent(xdisplay, DefaultRootWindow(xdisplay));
+ if (!xres) {
+ ERROR("Unable to get screen resources");
+ }
+
+ // Loop through xrandr outputs and check whether the xrandr
+ // output name matches the drm connector name
+ bool increment_xrandr_name = false;
+ for (int i = 0; i < xres->noutput; ++i) {
+ int oid = xres->outputs[i];
+ XRROutputInfo *oinfo = XRRGetOutputInfo(xdisplay, xres, oid);
+ // the QXL device doesn't use the drm names directly, but
+ // starts numbering from 0 instead of 1, so we need to
+ // detect this condition and add 1 to all output names in
+ // this scenario before comparing
+ if (i == 0) {
+ // check the first output to see if it ends with '-0'
+ char *postfix = oinfo->name + (strlen(oinfo->name) - 2);
+ if (strcmp(postfix, "-0") == 0) {
+ increment_xrandr_name = true;
+ }
+ }
+ char xname[100];
+ if (increment_xrandr_name) {
+ char *id_pos = strrchr(oinfo->name, '-') + 1;
+ int newid = atoi(id_pos) + 1;
+ if (snprintf(xname, sizeof(xname), "%s%i", oinfo->name, newid) < 0) {
+ ERROR("Unable to increment name");
+ }
+ } else {
+ strncpy(xname, oinfo->name, sizeof(xname) - 1);
+ }
+ if (strcmp(xname, cname) == 0) {
+ printf(" Found matching X Output: name=%s id=%i (%s)\n",
+ oinfo->name,
+ (int)oid,
+ connections[oinfo->connection + 1]);
+ XRRFreeOutputInfo(oinfo);
+ break;
+ }
+ XRRFreeOutputInfo(oinfo);
+ }
+
+ XRRFreeScreenResources(xres);
+ xres = NULL;
+
+ // we found the right card, abort the loop
+ found = true;
+ break;
+ }
+ }
+ if (!found) {
+ ERROR("Couldn't find a card with the given PCI address");
+ return EXIT_SUCCESS;
+ }
+}
--
2.14.4
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