Updated perfetto's GN build files to support traced compilation in QNX

Created new argument 'is_qnx' to handle all QNX-specific compilation
steps in GN build system. Currently, compilation for QNX is only
supported via perfetto's standalone builds. Also, updated the perfetto's
codebase to avoid running Linux-specific code in QNX. When compiling for
QNX the PERFETTO_OS_LINUX flag is still set to keep the QNX build as
compatible as possible with the Linux build.

With this change, one can build the QNX target of traced by compiling
with the following args.gn file:
'''
target_os = "qnx"
target_cpu = "arm64"
'''

Only arm64 architecture is supported and one needs to setup the QNX
developer environment before being able to compile.

NOTE: traced_relay compiles but still does not run with this change.

Test: tools/ninja -C out/qnx traced traced_relay perfetto
Bug: 382283537
Change-Id: I08bd3672a60b69cb92ba87eaeda9cec5b893afbc

gn/BUILD.gn

@@ -51,9 +51,14 @@ action("gen_buildflags") {
   # We can't just use (is_linux || is_android) in perfetto.gni because that
   # doesn't work in Android Mac host builds. We lose the GN notion of OS once
   # we run the tools/gen_xxx generators.
+  #
+  # Currently, QNX has the OS_LINUX flag enabled to remain as compatible as
+  # possible. Watchdog is an exception where it uses Linux-specific system
+  # calls. Therefore we skip enabling the watchdog in QNX.
   if (enable_perfetto_watchdog) {
-    perfetto_watchdog = "PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() || " +
-                        "PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX()"
+    perfetto_watchdog =
+        "PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() || " +
+        "PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX()"
   } else {
     perfetto_watchdog = "0"
   }

gn/perfetto.gni

@@ -197,7 +197,7 @@ declare_args() {
   enable_perfetto_integration_tests =
       perfetto_build_standalone || perfetto_build_with_android
 
-  enable_perfetto_benchmarks = perfetto_build_standalone && !is_win
+  enable_perfetto_benchmarks = perfetto_build_standalone && !is_win && !is_qnx
 
   enable_perfetto_fuzzers =
       perfetto_build_standalone && defined(is_fuzzer) && is_fuzzer
@@ -237,7 +237,7 @@ declare_args() {
   # the stack and prints the stack trace on stderr. Requires a dependency on
   # libbacktrace when enabled.
   enable_perfetto_stderr_crash_dump =
-      is_debug && perfetto_build_standalone && !is_wasm && !is_win
+      is_debug && perfetto_build_standalone && !is_wasm && !is_win && !is_qnx
 
   # Enables more aggressive compiler flags that assume recent Intel CPUs.
   # Runtime checks during initialization will print an error message and exit
@@ -269,12 +269,13 @@ declare_args() {
 
   # The traced_probes daemon is very Linux-specific, as it depends on ftrace and
   # various /proc interfaces. There is no point making its code platform-neutral
-  # as it won't do anything useful on Windows.
+  # as it won't do anything useful on Windows or QNX.
   # The only reason why we still build it on Mac OS is to be able to run the
   # unittests there and making dev on mac less cumbersome. The traced_probes
   # code happens to build cleanly and for now the mainteinance cost on Mac is
   # extremely low.
-  enable_perfetto_traced_probes = enable_perfetto_platform_services && !is_win
+  enable_perfetto_traced_probes =
+      enable_perfetto_platform_services && !is_win && !is_qnx
 
   # The relay service is enabled when platform services are enabled.
   # TODO(chinglinyu) check if we can enable on Windows.

gn/proto_library.gni

@@ -182,14 +182,14 @@ template("ipc_library") {
     } else {
       link_deps += [ "$perfetto_root_path/src/ipc:common" ]
     }
-    if (is_win) {
-      # TODO(primiano): investigate this. In Windows standalone builds, some
-      # executable targets end up in a state where no code pulls a dep on the
-      # ipc:client (in turn that seems a subtle consequence of not having
-      # traced_probes on Windows). This dep here is effectively needed because
-      # the client-side code in the generated .ipc.cc effectively depends on the
-      # client-side IPC library. Perhaps we just should do this unconditionally
-      # on all platforms?
+    if (is_win || is_qnx) {
+      # TODO(primiano): investigate this. In Windows and QNX standalone builds,
+      # some executable targets end up in a state where no code pulls a dep on
+      # the ipc:client (in turn that seems a subtle consequence of not having
+      # traced_probes on Windows or QNX). This dep here is effectively needed
+      # because the client-side code in the generated .ipc.cc effectively
+      # depends on the client-side IPC library. Perhaps we just should do this
+      # unconditionally on all platforms?
       if (perfetto_component_type == "static_library") {
         link_deps += [ "$perfetto_root_path/src/ipc:perfetto_ipc" ]
       } else {

gn/standalone/BUILD.gn

@@ -194,7 +194,7 @@ config("default") {
   ldflags = []
   libs = []
 
-  if ((is_android || is_linux) && !is_wasm) {
+  if ((is_android || is_linux || is_qnx) && !is_wasm) {
     ldflags += [
       "-Wl,--build-id",
       "-Wl,-z,max-page-size=16384",
@@ -335,6 +335,16 @@ config("default") {
     ]
   }
 
+  if (is_qnx) {
+    cflags += [
+      "-D_QNX_SOURCE",
+      "-D_FILE_OFFSET_BITS=64",
+      "-D_LARGEFILE_SOURCE",
+      "-D_LARGEFILE64_SOURCE",
+    ]
+    libs += [ "socket" ]
+  }
+
   if (is_win && !is_clang) {
     # When using MSVC we need to manually pass the include dirs. clang-cl.exe
     # doesn't need them because it's smart enough to figure out the right path
@@ -352,7 +362,7 @@ config("default") {
         cflags += [ "-gcodeview-ghash" ]
         ldflags = [ "/DEBUG:GHASH" ]
       }
-    } else {
+    } else if (!is_qnx) {
       libs += [ "dl" ]
     }
   }
@@ -431,6 +441,12 @@ config("release") {
     ]
   } else if (is_mac) {
     ldflags = [ "-dead_strip" ]
+  } else if (is_qnx) {
+    # QNX doesn't support the --icf linker option
+    ldflags = [
+      "-Wl,--gc-sections",
+      "-Wl,-O1",
+    ]
   } else if (!is_win && !is_wasm) {
     ldflags = [
       "-Wl,--gc-sections",

gn/standalone/BUILDCONFIG.gn

@@ -14,10 +14,12 @@
 
 declare_args() {
   is_debug = true
-  is_clang = true
   is_system_compiler = false
   is_lto = false
 
+  # Currently QNX is only supported via their gcc-compatible compiler.
+  is_clang = target_os != "qnx"
+
   # This is defined here because it's needed below for determining the value of
   # |is_cross_compiling|.
   target_triplet = ""
@@ -39,6 +41,7 @@ is_mac = current_os == "mac"
 is_mac_host = host_os == "mac"
 is_win = current_os == "win"
 is_win_host = host_os == "win"
+is_qnx = current_os == "qnx"
 
 # Building with Windows/Fuchsia/nacl is currently only supported in the Chromium
 # tree so always set this to false.

gn/standalone/toolchain/BUILD.gn

@@ -149,6 +149,8 @@ declare_args() {
     _target_triplet = "i686-linux-android"
   } else if (target_os == "android" && target_cpu == "x64") {
     _target_triplet = "x86_64-linux-android"
+  } else if (target_os == "qnx" && target_cpu == "arm64") {
+    _target_triplet = "ntoaarch64"
   } else {
     assert(
         false,
@@ -160,6 +162,9 @@ declare_args() {
   if (sysroot != "") {
     # If the user specifies a sysroot, use that for both host and target.
     target_sysroot = sysroot
+  } else if (is_qnx) {
+    # Do not set any sysroot for QNX.
+    target_sysroot = ""
   } else {
     # If no explicit sysroot has been set, use the guessed sysroot from the ones
     # pulled by //tools/install-build-deps (only for Linux).
@@ -190,6 +195,12 @@ declare_args() {
       target_cxx = "$android_llvm_dir/bin/clang++"
       target_linker = "$android_llvm_dir/bin/ld.lld"
       target_strip = "$android_llvm_dir/bin/llvm-strip"
+    } else if (is_qnx) {
+      target_ar = "${_target_triplet}-ar"
+      target_cc = "qcc -V8.3.0,gcc_${_target_triplet}le"
+      target_cxx = "q++ -V8.3.0,gcc_${_target_triplet}le_cxx"
+      target_linker = "${_target_triplet}-ld"
+      target_strip = "${_target_triplet}-strip"
     } else {
       assert(_target_triplet != "",
              "target_triplet must be non-empty when cross-compiling")
@@ -207,6 +218,7 @@ declare_args() {
         target_ar = "${_target_triplet}-ar"
         target_cc = "${_target_triplet}-gcc"
         target_cxx = "${_target_triplet}-g++"
+        target_strip = "${_target_triplet}-strip"
       }
     }
   }
@@ -253,7 +265,12 @@ template("gcc_like_toolchain") {
 
     tool("cc") {
       depfile = "{{output}}.d"
-      command = "$cc_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} ${external_cflags} -c {{source}} -o {{output}}"
+      if (is_qnx) {
+        depfile_args = "-Wp,-MMD,$depfile -Wp,-MF,$depfile"
+      } else {
+        depfile_args = "-MMD -MF $depfile"
+      }
+      command = "$cc_wrapper $cc $depfile_args {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} ${external_cflags} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       outputs =
           [ "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o" ]
@@ -262,7 +279,12 @@ template("gcc_like_toolchain") {
 
     tool("cxx") {
       depfile = "{{output}}.d"
-      command = "$cc_wrapper $cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}  ${external_cflags} ${external_cxxflags} -c {{source}} -o {{output}}"
+      if (is_qnx) {
+        depfile_args = "-Wp,-MMD,$depfile -Wp,-MF,$depfile"
+      } else {
+        depfile_args = "-MMD -MF $depfile"
+      }
+      command = "$cc_wrapper $cxx $depfile_args {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}  ${external_cflags} ${external_cxxflags} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       outputs =
           [ "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o" ]
@@ -271,7 +293,12 @@ template("gcc_like_toolchain") {
 
     tool("asm") {
       depfile = "{{output}}.d"
-      command = "$cc_wrapper $cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
+      if (is_qnx) {
+        depfile_args = "-Wp,-MMD,$depfile -Wp,-MF,$depfile"
+      } else {
+        depfile_args = "-MMD -MF $depfile"
+      }
+      command = "$cc_wrapper $cc $depfile_args {{defines}} {{include_dirs}} {{asmflags}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       outputs =
           [ "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.o" ]

include/perfetto/base/build_config.h

@@ -27,21 +27,25 @@
 #if defined(__ANDROID__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
 #elif defined(__APPLE__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
 // Include TARGET_OS_IPHONE when on __APPLE__ systems.
 #include <TargetConditionals.h>
 #if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE
@@ -54,46 +58,67 @@
 #elif defined(__linux__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 1
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
+#elif defined(__QNXNTO__)
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 1
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 1
 #elif defined(_WIN32)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
 #elif defined(__EMSCRIPTEN__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
 #elif defined(__Fuchsia__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_IOS() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WASM() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_FUCHSIA() 1
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_NACL() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_QNX() 0
 #elif defined(__native_client__)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX() 0
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_WIN() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_APPLE() 0
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_MAC() 0

include/perfetto/base/build_configs/android_tree/perfetto_build_flags.h

@@ -26,7 +26,7 @@
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_STANDALONE_BUILD() (0)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_START_DAEMONS() (0)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_IPC() (1)
-#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_WATCHDOG() (PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() || PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX())
+#define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_WATCHDOG() (PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_ANDROID() || PERFETTO_BUILDFLAG_DEFINE_PERFETTO_OS_LINUX_BUT_NOT_QNX())
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_COMPONENT_BUILD() (0)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_ENABLE_ETM_IMPORTER() (0)
 #define PERFETTO_BUILDFLAG_DEFINE_PERFETTO_FORCE_DLOG_ON() (0)

include/perfetto/base/thread_utils.h

@@ -29,6 +29,9 @@ __declspec(dllimport) unsigned long __stdcall GetCurrentThreadId();
 }
 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_FUCHSIA)
 #include <zircon/types.h>
+#elif PERFETTO_BUILDFLAG(PERFETTO_OS_QNX)
+#include <sys/types.h>
+#include <unistd.h>
 #elif PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
     PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
 #include <sys/syscall.h>
@@ -41,7 +44,8 @@ __declspec(dllimport) unsigned long __stdcall GetCurrentThreadId();
 namespace perfetto {
 namespace base {
 
-#if PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
+#if PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) || \
+    PERFETTO_BUILDFLAG(PERFETTO_OS_QNX)
 using PlatformThreadId = pid_t;
 inline PlatformThreadId GetThreadId() {
   return gettid();

include/perfetto/base/time.h

@@ -187,6 +187,33 @@ inline TimeNanos GetBootTimeNs() {
   return TimeNanos(0);
 }
 
+#elif PERFETTO_BUILDFLAG(PERFETTO_OS_QNX)
+
+constexpr clockid_t kWallTimeClockSource = CLOCK_MONOTONIC;
+
+inline TimeNanos GetTimeInternalNs(clockid_t clk_id) {
+  struct timespec ts = {};
+  PERFETTO_CHECK(clock_gettime(clk_id, &ts) == 0);
+  return FromPosixTimespec(ts);
+}
+
+inline TimeNanos GetWallTimeNs() {
+  return GetTimeInternalNs(kWallTimeClockSource);
+}
+
+inline TimeNanos GetWallTimeRawNs() {
+  return GetTimeInternalNs(CLOCK_MONOTONIC);
+}
+
+inline TimeNanos GetThreadCPUTimeNs() {
+  return GetTimeInternalNs(CLOCK_THREAD_CPUTIME_ID);
+}
+
+// TODO: Clock that counts time during suspend is not implemented on QNX.
+inline TimeNanos GetBootTimeNs() {
+  return GetWallTimeNs();
+}
+
 #else  // posix
 
 constexpr clockid_t kWallTimeClockSource = CLOCK_MONOTONIC;

include/perfetto/ext/base/event_fd.h

@@ -49,7 +49,10 @@ class EventFd {
   // the pipe for fallback mode.
   ScopedPlatformHandle event_handle_;
 
-#if !PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) &&   \
+// QNX is specified because it is a non-Linux UNIX platform but it
+// still sets the PERFETTO_OS_LINUX flag to be as compatible as possible
+// with the Linux build.
+#if !PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX_BUT_NOT_QNX) &&   \
     !PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID) && \
     !PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
   // On Mac and other non-Linux UNIX platforms a pipe-based fallback is used.