diff --git a/fastboot/Android.mk b/fastboot/Android.mk
index dd8bad9..bc88002 100644
--- a/fastboot/Android.mk
+++ b/fastboot/Android.mk
@@ -58,7 +58,6 @@
 
 LOCAL_STATIC_LIBRARIES := \
     libziparchive \
-    libext4_utils \
     libsparse \
     libutils \
     liblog \
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index c3b1bfb..40c18e0 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -1354,7 +1354,7 @@
 
 static unsigned fb_get_flash_block_size(Transport* transport, std::string name) {
     std::string sizeString;
-    if (!fb_getvar(transport, name.c_str(), &sizeString)) {
+    if (!fb_getvar(transport, name.c_str(), &sizeString) || sizeString.empty()) {
         /* This device does not report flash block sizes, so return 0 */
         return 0;
     }
@@ -1365,9 +1365,8 @@
         fprintf(stderr, "Couldn't parse %s '%s'.\n", name.c_str(), sizeString.c_str());
         return 0;
     }
-    if (size < 4096 || (size & (size - 1)) != 0) {
-        fprintf(stderr, "Invalid %s %u: must be a power of 2 and at least 4096.\n",
-                name.c_str(), size);
+    if ((size & (size - 1)) != 0) {
+        fprintf(stderr, "Invalid %s %u: must be a power of 2.\n", name.c_str(), size);
         return 0;
     }
     return size;
diff --git a/fastboot/fs.cpp b/fastboot/fs.cpp
index 709f061..2d77dd6 100644
--- a/fastboot/fs.cpp
+++ b/fastboot/fs.cpp
@@ -23,7 +23,6 @@
 #include <android-base/file.h>
 #include <android-base/stringprintf.h>
 #include <android-base/unique_fd.h>
-#include <ext4_utils/make_ext4fs.h>
 #include <sparse/sparse.h>
 
 using android::base::StringPrintf;
@@ -120,6 +119,8 @@
         int raid_stripe_width = eraseBlkSize / block_size;
         // stride should be the max of 8kb and logical block size
         if (logicalBlkSize != 0 && logicalBlkSize < 8192) raid_stride = 8192 / block_size;
+        // stripe width should be >= stride
+        if (raid_stripe_width < raid_stride) raid_stripe_width = raid_stride;
         ext_attr += StringPrintf(",stride=%d,stripe-width=%d", raid_stride, raid_stripe_width);
     }
     mke2fs_args.push_back("-E");
diff --git a/libbacktrace/UnwindStack.cpp b/libbacktrace/UnwindStack.cpp
index d17c211..3a38839 100644
--- a/libbacktrace/UnwindStack.cpp
+++ b/libbacktrace/UnwindStack.cpp
@@ -44,13 +44,13 @@
 #include "UnwindStackMap.h"
 
 bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
-                       std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames) {
-  std::vector<std::string> skip_names{"libunwindstack.so", "libbacktrace.so"};
+                       std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,
+                       std::vector<std::string>* skip_names) {
   UnwindStackMap* stack_map = reinterpret_cast<UnwindStackMap*>(back_map);
   auto process_memory = stack_map->process_memory();
   unwindstack::Unwinder unwinder(MAX_BACKTRACE_FRAMES + num_ignore_frames, stack_map->stack_maps(),
                                  regs, stack_map->process_memory());
-  unwinder.Unwind(&skip_names, &stack_map->GetSuffixesToIgnore());
+  unwinder.Unwind(skip_names, &stack_map->GetSuffixesToIgnore());
 
   if (num_ignore_frames >= unwinder.NumFrames()) {
     frames->resize(0);
@@ -104,7 +104,8 @@
   }
 
   error_ = BACKTRACE_UNWIND_NO_ERROR;
-  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames);
+  std::vector<std::string> skip_names{"libunwindstack.so", "libbacktrace.so"};
+  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, &skip_names);
 }
 
 UnwindStackPtrace::UnwindStackPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
@@ -124,5 +125,5 @@
   }
 
   error_ = BACKTRACE_UNWIND_NO_ERROR;
-  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames);
+  return Backtrace::Unwind(regs.get(), GetMap(), &frames_, num_ignore_frames, nullptr);
 }
diff --git a/libbacktrace/include/backtrace/Backtrace.h b/libbacktrace/include/backtrace/Backtrace.h
index 73a58b5..e073533 100644
--- a/libbacktrace/include/backtrace/Backtrace.h
+++ b/libbacktrace/include/backtrace/Backtrace.h
@@ -109,7 +109,8 @@
   virtual bool Unwind(size_t num_ignore_frames, ucontext_t* context = NULL) = 0;
 
   static bool Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
-                     std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames);
+                     std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,
+                     std::vector<std::string>* skip_names);
 
   // Get the function name and offset into the function given the pc.
   // If the string is empty, then no valid function name was found,
diff --git a/libpixelflinger/Android.mk b/libpixelflinger/Android.mk
index 55891db..c7306cd 100644
--- a/libpixelflinger/Android.mk
+++ b/libpixelflinger/Android.mk
@@ -25,6 +25,8 @@
 	buffer.cpp
 
 PIXELFLINGER_CFLAGS := -fstrict-aliasing -fomit-frame-pointer
+PIXELFLINGER_CFLAGS += -Wall -Werror
+PIXELFLINGER_CFLAGS += -Wno-unused-function
 
 PIXELFLINGER_SRC_FILES_arm := \
 	codeflinger/ARMAssembler.cpp \
diff --git a/libpixelflinger/codeflinger/Arm64Assembler.cpp b/libpixelflinger/codeflinger/Arm64Assembler.cpp
index bff87bb..aebc129 100644
--- a/libpixelflinger/codeflinger/Arm64Assembler.cpp
+++ b/libpixelflinger/codeflinger/Arm64Assembler.cpp
@@ -151,11 +151,11 @@
 
 namespace android {
 
-static const char* shift_codes[] =
+static __unused const char* shift_codes[] =
 {
     "LSL", "LSR", "ASR", "ROR"
 };
-static const char *cc_codes[] =
+static __unused const char *cc_codes[] =
 {
     "EQ", "NE", "CS", "CC", "MI",
     "PL", "VS", "VC", "HI", "LS",
@@ -984,7 +984,7 @@
 // A64 instructions
 // ----------------------------------------------------------------------------
 
-static const char * dataTransferOpName[] =
+static __unused const char * dataTransferOpName[] =
 {
     "LDR","LDRB","LDRH","STR","STRB","STRH"
 };
diff --git a/libpixelflinger/codeflinger/GGLAssembler.cpp b/libpixelflinger/codeflinger/GGLAssembler.cpp
index 91fbd53..04e285d 100644
--- a/libpixelflinger/codeflinger/GGLAssembler.cpp
+++ b/libpixelflinger/codeflinger/GGLAssembler.cpp
@@ -94,8 +94,6 @@
 
 int GGLAssembler::scanline_core(const needs_t& needs, context_t const* c)
 {
-    int64_t duration = ggl_system_time();
-
     mBlendFactorCached = 0;
     mBlending = 0;
     mMasking = 0;
@@ -353,7 +351,6 @@
     fragment_parts_t& parts, const needs_t& needs)
 {
     Scratch scratches(registerFile());
-    int Rctx = mBuilderContext.Rctx;
 
     // compute count
     comment("compute ct (# of pixels to process)");
diff --git a/libpixelflinger/codeflinger/load_store.cpp b/libpixelflinger/codeflinger/load_store.cpp
index da21e1d..4db0a49 100644
--- a/libpixelflinger/codeflinger/load_store.cpp
+++ b/libpixelflinger/codeflinger/load_store.cpp
@@ -232,7 +232,6 @@
 void GGLAssembler::downshift(
         pixel_t& d, int component, component_t s, const reg_t& dither)
 {
-    const needs_t& needs = mBuilderContext.needs;
     Scratch scratches(registerFile());
 
     int sh = s.h;
diff --git a/libpixelflinger/codeflinger/texturing.cpp b/libpixelflinger/codeflinger/texturing.cpp
index 4c357af..e6997bd 100644
--- a/libpixelflinger/codeflinger/texturing.cpp
+++ b/libpixelflinger/codeflinger/texturing.cpp
@@ -41,7 +41,6 @@
 void GGLAssembler::init_iterated_color(fragment_parts_t& parts, const reg_t& x)
 {
     context_t const* c = mBuilderContext.c;
-    const needs_t& needs = mBuilderContext.needs;
 
     if (mSmooth) {
         // NOTE: we could take this case in the mDithering + !mSmooth case,
@@ -324,9 +323,7 @@
         tex_coord_t* coords,
         const reg_t& x, const reg_t& y)
 {
-    context_t const* c = mBuilderContext.c;
     const needs_t& needs = mBuilderContext.needs;
-    int Rctx = mBuilderContext.Rctx;
     int Rx = x.reg;
     int Ry = y.reg;
 
@@ -402,10 +399,6 @@
 void GGLAssembler::build_textures(  fragment_parts_t& parts,
                                     Scratch& regs)
 {
-    context_t const* c = mBuilderContext.c;
-    const needs_t& needs = mBuilderContext.needs;
-    int Rctx = mBuilderContext.Rctx;
-
     // We don't have a way to spill registers automatically
     // spill depth and AA regs, when we know we may have to.
     // build the spill list...
@@ -434,7 +427,6 @@
 
     Spill spill(registerFile(), *this, spill_list);
 
-    const bool multiTexture = mTextureMachine.activeUnits > 1;
     for (int i=0 ; i<GGL_TEXTURE_UNIT_COUNT; i++) {
         const texture_unit_t& tmu = mTextureMachine.tmu[i];
         if (tmu.format_idx == 0)
@@ -442,7 +434,7 @@
 
         pointer_t& txPtr = parts.coords[i].ptr;
         pixel_t& texel = parts.texel[i];
-            
+
         // repeat...
         if ((tmu.swrap == GGL_NEEDS_WRAP_11) &&
             (tmu.twrap == GGL_NEEDS_WRAP_11))
@@ -656,7 +648,6 @@
 void GGLAssembler::build_iterate_texture_coordinates(
     const fragment_parts_t& parts)
 {
-    const bool multiTexture = mTextureMachine.activeUnits > 1;
     for (int i=0 ; i<GGL_TEXTURE_UNIT_COUNT; i++) {
         const texture_unit_t& tmu = mTextureMachine.tmu[i];
         if (tmu.format_idx == 0)
diff --git a/libpixelflinger/include/private/pixelflinger/ggl_fixed.h b/libpixelflinger/include/private/pixelflinger/ggl_fixed.h
index 17b85dd..51e9e26 100644
--- a/libpixelflinger/include/private/pixelflinger/ggl_fixed.h
+++ b/libpixelflinger/include/private/pixelflinger/ggl_fixed.h
@@ -497,7 +497,6 @@
 {
 
     GGLfixed result;
-    int rshift;
 
     asm("smull  %x[result], %w[x], %w[y]                     \n"
         "lsr    %x[result], %x[result], %x[shift]            \n"
diff --git a/libpixelflinger/raster.cpp b/libpixelflinger/raster.cpp
index 26d8e45..e95c2c8 100644
--- a/libpixelflinger/raster.cpp
+++ b/libpixelflinger/raster.cpp
@@ -153,7 +153,6 @@
      GGLint h = where[3];
 
     // exclsively enable this tmu
-    const GGLSurface& cbSurface = c->state.buffers.color.s;
     c->procs.activeTexture(c, tmu);
     c->procs.disable(c, GGL_W_LERP);
 
diff --git a/libpixelflinger/scanline.cpp b/libpixelflinger/scanline.cpp
index c6cf5bf..4cc23c7 100644
--- a/libpixelflinger/scanline.cpp
+++ b/libpixelflinger/scanline.cpp
@@ -2144,7 +2144,6 @@
     const int32_t u = (c->state.texture[0].shade.is0>>16) + x;
     const int32_t v = (c->state.texture[0].shade.it0>>16) + y;
     uint32_t *src = reinterpret_cast<uint32_t*>(tex->data)+(u+(tex->stride*v));
-    int sR, sG, sB;
     uint32_t s, d;
 
     if (ct==1 || uintptr_t(dst)&2) {
diff --git a/libpixelflinger/tests/arch-arm64/assembler/Android.mk b/libpixelflinger/tests/arch-arm64/assembler/Android.mk
index bd0f24b..db5dc4d 100644
--- a/libpixelflinger/tests/arch-arm64/assembler/Android.mk
+++ b/libpixelflinger/tests/arch-arm64/assembler/Android.mk
@@ -14,6 +14,8 @@
 
 LOCAL_MODULE:= test-pixelflinger-arm64-assembler-test
 
+LOCAL_CFLAGS := -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_MULTILIB := 64
diff --git a/libpixelflinger/tests/arch-arm64/col32cb16blend/Android.mk b/libpixelflinger/tests/arch-arm64/col32cb16blend/Android.mk
index 3368eb0..3096232 100644
--- a/libpixelflinger/tests/arch-arm64/col32cb16blend/Android.mk
+++ b/libpixelflinger/tests/arch-arm64/col32cb16blend/Android.mk
@@ -11,6 +11,8 @@
 
 LOCAL_MODULE:= test-pixelflinger-arm64-col32cb16blend
 
+LOCAL_CFLAGS := -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_MULTILIB := 64
diff --git a/libpixelflinger/tests/arch-arm64/disassembler/Android.mk b/libpixelflinger/tests/arch-arm64/disassembler/Android.mk
index d8f7e69..78f12af 100644
--- a/libpixelflinger/tests/arch-arm64/disassembler/Android.mk
+++ b/libpixelflinger/tests/arch-arm64/disassembler/Android.mk
@@ -9,6 +9,8 @@
 
 LOCAL_MODULE:= test-pixelflinger-arm64-disassembler-test
 
+LOCAL_CFLAGS := -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_MULTILIB := 64
diff --git a/libpixelflinger/tests/arch-arm64/t32cb16blend/Android.mk b/libpixelflinger/tests/arch-arm64/t32cb16blend/Android.mk
index 8e5ec5e..664347f 100644
--- a/libpixelflinger/tests/arch-arm64/t32cb16blend/Android.mk
+++ b/libpixelflinger/tests/arch-arm64/t32cb16blend/Android.mk
@@ -11,6 +11,8 @@
 
 LOCAL_MODULE:= test-pixelflinger-arm64-t32cb16blend
 
+LOCAL_CFLAGS := -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 LOCAL_MULTILIB := 64
diff --git a/libpixelflinger/tests/codegen/Android.mk b/libpixelflinger/tests/codegen/Android.mk
index 2f9ca2f..72d71ef 100644
--- a/libpixelflinger/tests/codegen/Android.mk
+++ b/libpixelflinger/tests/codegen/Android.mk
@@ -13,6 +13,8 @@
 
 LOCAL_MODULE:= test-opengl-codegen
 
+LOCAL_CFLAGS:= -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 include $(BUILD_NATIVE_TEST)
diff --git a/libpixelflinger/tests/codegen/codegen.cpp b/libpixelflinger/tests/codegen/codegen.cpp
index efa6d87..dce4ed7 100644
--- a/libpixelflinger/tests/codegen/codegen.cpp
+++ b/libpixelflinger/tests/codegen/codegen.cpp
@@ -40,9 +40,9 @@
     const AssemblyKey<needs_t>& key() const { return mKey; }
 };
 
+#if ANDROID_ARM_CODEGEN
 static void ggl_test_codegen(uint32_t n, uint32_t p, uint32_t t0, uint32_t t1)
 {
-#if ANDROID_ARM_CODEGEN
     GGLContext* c;
     gglInit(&c);
     needs_t needs;
@@ -73,10 +73,12 @@
         printf("error %08x (%s)\n", err, strerror(-err));
     }
     gglUninit(c);
-#else
-    printf("This test runs only on ARM, Arm64 or MIPS\n");
-#endif
 }
+#else
+static void ggl_test_codegen(uint32_t, uint32_t, uint32_t, uint32_t) {
+    printf("This test runs only on ARM, Arm64 or MIPS\n");
+}
+#endif
 
 int main(int argc, char** argv)
 {
diff --git a/libpixelflinger/tests/gglmul/Android.mk b/libpixelflinger/tests/gglmul/Android.mk
index 75bd39e..67f358f 100644
--- a/libpixelflinger/tests/gglmul/Android.mk
+++ b/libpixelflinger/tests/gglmul/Android.mk
@@ -11,6 +11,8 @@
 
 LOCAL_MODULE:= test-pixelflinger-gglmul
 
+LOCAL_CFLAGS:= -Wall -Werror
+
 LOCAL_MODULE_TAGS := tests
 
 include $(BUILD_NATIVE_TEST)
diff --git a/libpixelflinger/trap.cpp b/libpixelflinger/trap.cpp
index 234bfdd..06ad237 100644
--- a/libpixelflinger/trap.cpp
+++ b/libpixelflinger/trap.cpp
@@ -349,7 +349,6 @@
 
 static void linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
 {
-    GGL_CONTEXT(c, con);
     GGLcoord v[4][2];
     v[0][0] = v0[0];    v[0][1] = v0[1];
     v[1][0] = v1[0];    v[1][1] = v1[1];
@@ -377,7 +376,6 @@
 
 static void aa_linex(void *con, const GGLcoord* v0, const GGLcoord* v1, GGLcoord width)
 {
-    GGL_CONTEXT(c, con);
     GGLcoord v[4][2];
     v[0][0] = v0[0];    v[0][1] = v0[1];
     v[1][0] = v1[0];    v[1][1] = v1[1];
diff --git a/toolbox/Android.mk b/toolbox/Android.mk
index 94029d8..c4795a7 100644
--- a/toolbox/Android.mk
+++ b/toolbox/Android.mk
@@ -59,3 +59,12 @@
 $(INPUT_H_LABELS_H): $(LOCAL_PATH)/Android.mk $(LOCAL_PATH)/generate-input.h-labels.py $(UAPI_INPUT_EVENT_CODES_H)
 $(INPUT_H_LABELS_H):
 	$(transform-generated-source)
+
+# We only want 'r' on userdebug and eng builds.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := r.c
+LOCAL_CFLAGS += $(common_cflags)
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/upstream-netbsd/include/
+LOCAL_MODULE := r
+LOCAL_MODULE_TAGS := debug
+include $(BUILD_EXECUTABLE)
diff --git a/toolbox/r.c b/toolbox/r.c
new file mode 100644
index 0000000..b96cdb2
--- /dev/null
+++ b/toolbox/r.c
@@ -0,0 +1,102 @@
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#if __LP64__
+#define strtoptr strtoull
+#else
+#define strtoptr strtoul
+#endif
+
+static int usage()
+{
+    fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
+    return -1;
+}
+
+int main(int argc, char *argv[])
+{
+    if(argc < 2) return usage();
+
+    int width = 4;
+    if(!strcmp(argv[1], "-b")) {
+        width = 1;
+        argc--;
+        argv++;
+    } else if(!strcmp(argv[1], "-s")) {
+        width = 2;
+        argc--;
+        argv++;
+    }
+
+    if(argc < 2) return usage();
+    uintptr_t addr = strtoptr(argv[1], 0, 16);
+
+    uintptr_t endaddr = 0;
+    char* end = strchr(argv[1], '-');
+    if (end)
+        endaddr = strtoptr(end + 1, 0, 16);
+
+    if (!endaddr)
+        endaddr = addr + width - 1;
+
+    if (endaddr <= addr) {
+        fprintf(stderr, "end address <= start address\n");
+        return -1;
+    }
+
+    bool set = false;
+    uint32_t value = 0;
+    if(argc > 2) {
+        set = true;
+        value = strtoul(argv[2], 0, 16);
+    }
+
+    int fd = open("/dev/mem", O_RDWR | O_SYNC);
+    if(fd < 0) {
+        fprintf(stderr,"cannot open /dev/mem\n");
+        return -1;
+    }
+
+    off64_t mmap_start = addr & ~(PAGE_SIZE - 1);
+    size_t mmap_size = endaddr - mmap_start + 1;
+    mmap_size = (mmap_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
+
+    void* page = mmap64(0, mmap_size, PROT_READ | PROT_WRITE,
+                        MAP_SHARED, fd, mmap_start);
+
+    if(page == MAP_FAILED){
+        fprintf(stderr,"cannot mmap region\n");
+        return -1;
+    }
+
+    while (addr <= endaddr) {
+        switch(width){
+        case 4: {
+            uint32_t* x = (uint32_t*) (((uintptr_t) page) + (addr & 4095));
+            if(set) *x = value;
+            fprintf(stderr,"%08"PRIxPTR": %08x\n", addr, *x);
+            break;
+        }
+        case 2: {
+            uint16_t* x = (uint16_t*) (((uintptr_t) page) + (addr & 4095));
+            if(set) *x = value;
+            fprintf(stderr,"%08"PRIxPTR": %04x\n", addr, *x);
+            break;
+        }
+        case 1: {
+            uint8_t* x = (uint8_t*) (((uintptr_t) page) + (addr & 4095));
+            if(set) *x = value;
+            fprintf(stderr,"%08"PRIxPTR": %02x\n", addr, *x);
+            break;
+        }
+        }
+        addr += width;
+    }
+    return 0;
+}