diff --git a/README b/README
index bdeb8cd..db6738c 100644
--- a/README
+++ b/README
@@ -103,6 +103,11 @@ Testing
 Troubleshooting
 ---------------
 
+# Build
+
+    Install toolchain for the 32-bit target, e.g. gcc-multilib, lib32-glibc,
+    32-bit and develop packages of libfuse and libsdl2, fasm.
+
 # umka_os
 
 To create tap devices.
diff --git a/TODO b/TODO
index d03bff9..4d23595 100644
--- a/TODO
+++ b/TODO
@@ -1,9 +1,10 @@
+make mkfs.* use config files (-c for mkfs.xfs)
+export and initialize mouse_delay and mouse_speed_factor (test and cover func mouse_acceleration)
 lsstat to decrease tests size
-separate dirs for each image and test
+separate dirs for each image
+include umka_os to tests
+tests with writing to block devices (read-only base image + discardable image for writing)
 library loader
-custom test runner
-make mkfs.xfs use config file via -c option
-writing tests
-compare with reference XFS implementation
-stressing via ref impl
+validate against the reference XFS implementation
+stressing via ref impl (how?)
 multithreaded: kofu one.t two.t
diff --git a/makefile b/makefile
index 8839124..abae03c 100644
--- a/makefile
+++ b/makefile
@@ -84,7 +84,7 @@ umka_os: umka_os.o umka.o shell.o deps/lodepng/lodepng.o vdisk.o vdisk/raw.o \
          vnet/file.o vnet/null.o trace.o trace_lbr.o $(HOST)/pci.o \
          $(HOST)/thread.o umkaio.o umkart.o deps/isocline/src/isocline.o \
          deps/optparse/optparse.o
-	$(CC) $(LDFLAGS_32) `sdl2-config --libs` $^ -o $@ -T umka.ld
+	$(CC) $(LDFLAGS_32) $^ `sdl2-config --libs` -o $@ -T umka.ld
 
 umka_gen_devices_dat: umka_gen_devices_dat.o umka.o $(HOST)/pci.o \
                       $(HOST)/thread.o umkart.o
diff --git a/shell.c b/shell.c
index 2d8130a..73ae448 100644
--- a/shell.c
+++ b/shell.c
@@ -51,124 +51,12 @@
 
 #define SHELL_CMD_BUF_LEN 0x10
 
-enum {
-    UMKA_CMD_NONE,
-    UMKA_CMD_SET_MOUSE_DATA,
-    UMKA_CMD_WAIT_FOR_IDLE,
-    UMKA_CMD_WAIT_FOR_OS_IDLE,
-    UMKA_CMD_WAIT_FOR_WINDOW,
-    UMKA_CMD_SYS_CSLEEP,
-    UMKA_CMD_SYS_PROCESS_INFO,
-    UMKA_CMD_SYS_GET_MOUSE_POS_SCREEN,
-    UMKA_CMD_SYS_LFN,
-};
-
 enum {
     SHELL_CMD_STATUS_EMPTY,
     SHELL_CMD_STATUS_READY,
     SHELL_CMD_STATUS_DONE,
 };
 
-struct cmd_set_mouse_data_arg {
-    uint32_t btn_state;
-    int32_t xmoving;
-    int32_t ymoving;
-    int32_t vscroll;
-    int32_t hscroll;
-};
-
-struct cmd_set_mouse_data_ret {
-    char stub;
-};
-
-struct cmd_set_mouse_data {
-    struct cmd_set_mouse_data_arg arg;
-    struct cmd_set_mouse_data_ret ret;
-};
-
-struct cmd_sys_lfn_arg {
-    f70or80_t f70or80;
-    f7080s1arg_t *bufptr;
-    f7080ret_t *r;
-};
-
-struct cmd_sys_lfn_ret {
-    f7080ret_t status;
-};
-
-struct cmd_sys_lfn {
-    struct cmd_sys_lfn_arg arg;
-    struct cmd_sys_lfn_ret ret;
-};
-
-struct cmd_sys_process_info_arg {
-    int32_t pid;
-    void *param;
-};
-
-struct cmd_sys_process_info_ret {
-    char stub;
-};
-
-struct cmd_sys_process_info {
-    struct cmd_sys_process_info_arg arg;
-    struct cmd_sys_process_info_ret ret;
-};
-
-struct cmd_sys_get_mouse_pos_screen_arg {
-    char stub;
-};
-
-struct cmd_sys_get_mouse_pos_screen_ret {
-    struct point16s pos;
-};
-
-struct cmd_sys_get_mouse_pos_screen {
-    struct cmd_sys_get_mouse_pos_screen_arg arg;
-    struct cmd_sys_get_mouse_pos_screen_ret ret;
-};
-
-struct cmd_sys_csleep_arg {
-    uint32_t csec;
-};
-
-struct cmd_sys_csleep_ret {
-    char stub;
-};
-
-struct cmd_sys_csleep {
-    struct cmd_sys_csleep_arg arg;
-    struct cmd_sys_csleep_ret ret;
-};
-
-struct cmd_wait_for_window_arg {
-    char *wnd_title;
-};
-
-struct cmd_wait_for_window_ret {
-    char stub;
-};
-
-struct cmd_wait_for_window {
-    struct cmd_wait_for_window_arg arg;
-    struct cmd_wait_for_window_ret ret;
-};
-
-struct umka_cmd {
-    atomic_int status;
-    uint32_t type;
-    union {
-        // internal funcs
-        struct cmd_set_mouse_data set_mouse_data;
-        struct cmd_wait_for_window wait_for_window;
-        // syscalls
-        struct cmd_sys_csleep sys_csleep;
-        struct cmd_sys_process_info sys_process_info;
-        struct cmd_sys_lfn sys_lfn;
-        struct cmd_sys_get_mouse_pos_screen sys_get_mouse_pos_screen;
-    };
-};
-
 struct umka_cmd umka_cmd_buf[SHELL_CMD_BUF_LEN];
 
 char prompt_line[PATH_MAX];
@@ -181,21 +69,6 @@ typedef struct {
     void (*func) (struct shell_ctx *, int, char **);
 } func_table_t;
 
-void
-shell_run_cmd_sync(struct shell_ctx *ctx);
-
-static void
-shell_run_cmd(struct shell_ctx *ctx) {
-    struct umka_cmd *cmd = umka_cmd_buf;
-    atomic_store_explicit(&cmd->status, SHELL_CMD_STATUS_READY,
-                          memory_order_release);
-    if (atomic_load_explicit(ctx->running, memory_order_acquire) == UMKA_RUNNING_YES) {
-        pthread_cond_wait(&ctx->cmd_done, &ctx->cmd_mutex);
-    } else {
-        shell_run_cmd_sync(ctx);
-    }
-}
-
 static uint32_t
 shell_run_cmd_wait_test(void /* struct appdata * with wait_param is in ebx */) {
     appdata_t *app;
@@ -204,6 +77,9 @@ shell_run_cmd_wait_test(void /* struct appdata * with wait_param is in ebx */) {
     return (uint32_t)(atomic_load_explicit(&cmd->status, memory_order_acquire) == SHELL_CMD_STATUS_READY);
 }
 
+static void
+shell_run_cmd_sync(struct shell_ctx *ctx);
+
 static void
 thread_cmd_runner(void *arg) {
     umka_sti();
@@ -1387,17 +1263,16 @@ cmd_mouse_move(struct shell_ctx *ctx, int argc, char **argv) {
     }
     uint32_t btn_state = lbheld + (rbheld << 1) + (mbheld << 2) + (yabs << 30)
                          + (xabs << 31);
-    struct umka_cmd *cmd = umka_cmd_buf;
-    struct cmd_set_mouse_data_arg *c = &cmd->set_mouse_data.arg;
+    struct umka_cmd *cmd = shell_get_cmd(ctx);
     cmd->type = UMKA_CMD_SET_MOUSE_DATA;
+    struct cmd_set_mouse_data_arg *c = &cmd->set_mouse_data.arg;
     c->btn_state = btn_state;
     c->xmoving = xmoving;
     c->ymoving = ymoving;
     c->vscroll = vscroll;
     c->hscroll = hscroll;
     shell_run_cmd(ctx);
-    atomic_store_explicit(&cmd->status, SHELL_CMD_STATUS_EMPTY,
-                          memory_order_release);
+    shell_clear_cmd(cmd);
 }
 
 static void
@@ -4330,7 +4205,7 @@ func_table_t cmd_cmds[] = {
     { NULL,                             NULL },
 };
 
-void
+static void
 shell_run_cmd_sync(struct shell_ctx *ctx) {
     struct umka_cmd *cmd = umka_cmd_buf;
     switch (cmd->type) {
@@ -4384,6 +4259,30 @@ shell_run_cmd_sync(struct shell_ctx *ctx) {
     pthread_cond_signal(&ctx->cmd_done);
 }
 
+struct umka_cmd *
+shell_get_cmd(struct shell_ctx *shell) {
+    (void)shell;
+    return umka_cmd_buf;
+}
+
+void
+shell_run_cmd(struct shell_ctx *ctx) {
+    struct umka_cmd *cmd = umka_cmd_buf;
+    atomic_store_explicit(&cmd->status, SHELL_CMD_STATUS_READY,
+                          memory_order_release);
+    if (atomic_load_explicit(ctx->running, memory_order_acquire) == UMKA_RUNNING_YES) {
+        pthread_cond_wait(&ctx->cmd_done, &ctx->cmd_mutex);
+    } else {
+        shell_run_cmd_sync(ctx);
+    }
+}
+
+void
+shell_clear_cmd(struct umka_cmd *cmd) {
+    atomic_store_explicit(&cmd->status, SHELL_CMD_STATUS_EMPTY,
+                          memory_order_release);
+}
+
 static void
 cmd_help(struct shell_ctx *ctx, int argc, char **argv) {
     const char *usage = \
diff --git a/shell.h b/shell.h
index ca02e26..e312717 100644
--- a/shell.h
+++ b/shell.h
@@ -59,7 +59,125 @@ shell_close(struct shell_ctx *shell);
 void *
 run_test(struct shell_ctx *ctx);
 
+enum {
+    UMKA_CMD_NONE,
+    UMKA_CMD_SET_MOUSE_DATA,
+    UMKA_CMD_WAIT_FOR_IDLE,
+    UMKA_CMD_WAIT_FOR_OS_IDLE,
+    UMKA_CMD_WAIT_FOR_WINDOW,
+    UMKA_CMD_SYS_CSLEEP,
+    UMKA_CMD_SYS_PROCESS_INFO,
+    UMKA_CMD_SYS_GET_MOUSE_POS_SCREEN,
+    UMKA_CMD_SYS_LFN,
+};
+
+struct cmd_set_mouse_data_arg {
+    uint32_t btn_state;
+    int32_t xmoving;
+    int32_t ymoving;
+    int32_t vscroll;
+    int32_t hscroll;
+};
+
+struct cmd_set_mouse_data_ret {
+    char stub;
+};
+
+struct cmd_set_mouse_data {
+    struct cmd_set_mouse_data_arg arg;
+    struct cmd_set_mouse_data_ret ret;
+};
+
+struct cmd_sys_lfn_arg {
+    f70or80_t f70or80;
+    f7080s1arg_t *bufptr;
+    f7080ret_t *r;
+};
+
+struct cmd_sys_lfn_ret {
+    f7080ret_t status;
+};
+
+struct cmd_sys_lfn {
+    struct cmd_sys_lfn_arg arg;
+    struct cmd_sys_lfn_ret ret;
+};
+
+struct cmd_sys_process_info_arg {
+    int32_t pid;
+    void *param;
+};
+
+struct cmd_sys_process_info_ret {
+    char stub;
+};
+
+struct cmd_sys_process_info {
+    struct cmd_sys_process_info_arg arg;
+    struct cmd_sys_process_info_ret ret;
+};
+
+struct cmd_sys_get_mouse_pos_screen_arg {
+    char stub;
+};
+
+struct cmd_sys_get_mouse_pos_screen_ret {
+    struct point16s pos;
+};
+
+struct cmd_sys_get_mouse_pos_screen {
+    struct cmd_sys_get_mouse_pos_screen_arg arg;
+    struct cmd_sys_get_mouse_pos_screen_ret ret;
+};
+
+struct cmd_sys_csleep_arg {
+    uint32_t csec;
+};
+
+struct cmd_sys_csleep_ret {
+    char stub;
+};
+
+struct cmd_sys_csleep {
+    struct cmd_sys_csleep_arg arg;
+    struct cmd_sys_csleep_ret ret;
+};
+
+struct cmd_wait_for_window_arg {
+    char *wnd_title;
+};
+
+struct cmd_wait_for_window_ret {
+    char stub;
+};
+
+struct cmd_wait_for_window {
+    struct cmd_wait_for_window_arg arg;
+    struct cmd_wait_for_window_ret ret;
+};
+
+struct umka_cmd {
+    atomic_int status;
+    uint32_t type;
+    union {
+        // internal funcs
+        struct cmd_set_mouse_data set_mouse_data;
+        struct cmd_wait_for_window wait_for_window;
+        // syscalls
+        struct cmd_sys_csleep sys_csleep;
+        struct cmd_sys_process_info sys_process_info;
+        struct cmd_sys_lfn sys_lfn;
+        struct cmd_sys_get_mouse_pos_screen sys_get_mouse_pos_screen;
+    };
+};
+
+struct umka_cmd *
+shell_get_cmd(struct shell_ctx *shell);
+
 void
-umka_run_cmd_sync(struct shell_ctx *ctx);
+shell_run_cmd(struct shell_ctx *ctx);
+
+void
+shell_clear_cmd(struct umka_cmd *cmd);
 
 #endif  // SHELL_H_INCLUDED
diff --git a/umka_os.c b/umka_os.c
index 72a7c26..f38a315 100644
--- a/umka_os.c
+++ b/umka_os.c
@@ -154,6 +154,17 @@ hw_int(int signo) {
     umka_sti();
 }
 
+void (*copy_display)(void *);
+
+static void
+update_display(SDL_Surface *window_surface, SDL_Window *window) {
+    SDL_LockSurface(window_surface);
+    copy_display(window_surface->pixels);
+    SDL_UnlockSurface(window_surface);
+    SDL_UpdateWindowSurface(window);
+    return;
+}
+
 static void *
 umka_display(void *arg) {
     (void)arg;
@@ -164,8 +175,8 @@ umka_display(void *arg) {
     }
 
     char title[64];
-    sprintf(title, "umka0 %ux%u %ubpp", kos_display.width, kos_display.height,
-            kos_display.bits_per_pixel);
+    sprintf(title, "umka %ux%u %ubpp, press Ctrl-Alt-g to (un)grab input",
+            kos_display.width, kos_display.height, kos_display.bits_per_pixel);
     SDL_Window *window = SDL_CreateWindow(title,
                                           SDL_WINDOWPOS_UNDEFINED,
                                           SDL_WINDOWPOS_UNDEFINED,
@@ -187,8 +198,6 @@ umka_display(void *arg) {
         return NULL;
     }
 
-    void (*copy_display)(void *) = NULL;
-
     switch (window_surface->format->format) {
     case SDL_PIXELFORMAT_RGB888:
         copy_display = copy_display_to_rgb888;
@@ -199,12 +208,109 @@ umka_display(void *arg) {
         break;
     }
 
+    bool input_grabbed = false;
+
+    SDL_Event event;
     while (1) {
-        SDL_LockSurface(window_surface);
-        copy_display(window_surface->pixels);
-        SDL_UnlockSurface(window_surface);
-        SDL_UpdateWindowSurface(window);
-        sleep(1);
+        struct umka_cmd *cmd;
+        struct cmd_set_mouse_data_arg *c;
+        uint32_t btn_state;
+        update_display(window_surface, window);
+        if (SDL_WaitEventTimeout(&event, 1000 /* ms */)) {
+            switch (event.type) {
+            case SDL_QUIT:
+                break;
+            case SDL_WINDOWEVENT:
+                break;
+            case SDL_MOUSEBUTTONDOWN:
+            case SDL_MOUSEBUTTONUP:
+                if (!input_grabbed) {
+                    break;
+                }
+                cmd = shell_get_cmd(os->shell);
+                cmd->type = UMKA_CMD_SET_MOUSE_DATA;
+                c = &cmd->set_mouse_data.arg;
+                c->btn_state = event.button.state;
+                c->xmoving = 0;
+                c->ymoving = 0;
+                c->vscroll = 0;
+                c->hscroll = 0;
+                shell_run_cmd(os->shell);
+                shell_clear_cmd(cmd);
+                break;
+            case SDL_MOUSEMOTION:
+                if (!input_grabbed) {
+                    break;
+                }
+                cmd = shell_get_cmd(os->shell);
+                cmd->type = UMKA_CMD_SET_MOUSE_DATA;
+                c = &cmd->set_mouse_data.arg;
+                c->btn_state = 0;
+                c->xmoving = event.motion.xrel;
+                c->ymoving = -event.motion.yrel;
+                c->vscroll = 0;
+                c->hscroll = 0;
+                shell_run_cmd(os->shell);
+                shell_clear_cmd(cmd);
+                break;
+            case SDL_MOUSEWHEEL:
+                if (!input_grabbed) {
+                    break;
+                }
+                btn_state = SDL_GetMouseState(NULL, NULL);
+                cmd = shell_get_cmd(os->shell);
+                cmd->type = UMKA_CMD_SET_MOUSE_DATA;
+                c = &cmd->set_mouse_data.arg;
+                c->btn_state = 0;
+                if ((btn_state & SDL_BUTTON_LMASK)) {
+                    c->btn_state |= 0x01;
+                }
+                /*
+                if ((btn_state & SDL_BUTTON_RMASK)) {
+                    c->btn_state |= 0x02;
+                }
+                if ((btn_state & SDL_BUTTON_MMASK)) {
+                    c->btn_state |= 0x04;
+                }
+                */
+                c->xmoving = 0;
+                c->ymoving = 0;
+                c->vscroll = event.wheel.y;
+                c->hscroll = event.wheel.x;
+                shell_run_cmd(os->shell);
+                shell_clear_cmd(cmd);
+                break;
+            case SDL_KEYDOWN:
+                if ((event.key.keysym.scancode == SDL_SCANCODE_G)
+                    && (event.key.keysym.mod & KMOD_CTRL)
+                    && (event.key.keysym.mod & KMOD_ALT)) {
+                    input_grabbed = !input_grabbed;
+                    SDL_SetWindowMouseGrab(window, input_grabbed);
+                    SDL_SetWindowKeyboardGrab(window, input_grabbed);
+                    SDL_SetRelativeMouseMode(input_grabbed);
+                }
+                if (!input_grabbed) {
+                    break;
+                }
+                break;
+            case SDL_KEYUP:
+                if (!input_grabbed) {
+                    break;
+                }
+                break;
+            case SDL_TEXTINPUT:
+                if (!input_grabbed) {
+                    break;
+                }
+                break;
+            default:
+                fprintf(stderr, "[sdl] unknown event type: 0x%x\n", event.type);
+                update_display(window_surface, window);
+            }
+        } else {
+            update_display(window_surface, window);
+        }
+//        sleep(1);
     }
     return NULL;
 }