This is an automated email from the ASF dual-hosted git repository.
xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git
The following commit(s) were added to refs/heads/master by this push:
new 9e43a4d31c sim: To avoid system calls being interrupted when use host
api
9e43a4d31c is described below
commit 9e43a4d31c17ec603c1f5b64a992aa7a000de827
Author: yintao <[email protected]>
AuthorDate: Wed Aug 23 12:36:36 2023 +0800
sim: To avoid system calls being interrupted when use host api
Signed-off-by: yintao <[email protected]>
---
arch/sim/src/sim/posix/sim_alsa.c | 130 +++++++++++++++++---------------
arch/sim/src/sim/posix/sim_hostmemory.c | 78 +++++++------------
arch/sim/src/sim/posix/sim_hostmisc.c | 41 ++++------
arch/sim/src/sim/sim_internal.h | 21 ++++++
4 files changed, 130 insertions(+), 140 deletions(-)
diff --git a/arch/sim/src/sim/posix/sim_alsa.c
b/arch/sim/src/sim/posix/sim_alsa.c
index 366d74bfe8..9fc1e148b4 100644
--- a/arch/sim/src/sim/posix/sim_alsa.c
+++ b/arch/sim/src/sim/posix/sim_alsa.c
@@ -33,6 +33,7 @@
#include <alsa/asoundlib.h>
+#include "sim_internal.h"
#include "sim_offload.h"
/****************************************************************************
@@ -161,40 +162,41 @@ static int sim_audio_config_format(struct sim_audio_s
*priv, snd_pcm_t *pcm)
break;
}
- ret = snd_pcm_hw_params_malloc(&hw_params);
+ ret = host_uninterruptible(snd_pcm_hw_params_malloc, &hw_params);
if (ret < 0)
{
return ret;
}
- ret = snd_pcm_hw_params_any(pcm, hw_params);
+ ret = host_uninterruptible(snd_pcm_hw_params_any, pcm, hw_params);
if (ret < 0)
{
goto fail;
}
- ret = snd_pcm_hw_params_set_access(pcm, hw_params,
- SND_PCM_ACCESS_RW_INTERLEAVED);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_access, pcm,
+ hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
if (ret < 0)
{
goto fail;
}
- ret = snd_pcm_hw_params_set_format(pcm, hw_params, format);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_format, pcm,
+ hw_params, format);
if (ret < 0)
{
goto fail;
}
- ret = snd_pcm_hw_params_set_rate(pcm, hw_params,
- priv->sample_rate, 0);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_rate, pcm,
+ hw_params, priv->sample_rate, 0);
if (ret < 0)
{
goto fail;
}
- ret = snd_pcm_hw_params_set_channels(pcm, hw_params,
- priv->channels);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_channels, pcm,
+ hw_params, priv->channels);
if (ret < 0)
{
goto fail;
@@ -203,8 +205,8 @@ static int sim_audio_config_format(struct sim_audio_s
*priv, snd_pcm_t *pcm)
total_size = priv->nbuffers * priv->buffer_size;
pframes = priv->buffer_size / priv->frame_size;
- ret = snd_pcm_hw_params_set_period_size_near(pcm, hw_params,
- &pframes, NULL);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_period_size_near,
+ pcm, hw_params, &pframes, NULL);
if (ret < 0)
{
goto fail;
@@ -212,17 +214,17 @@ static int sim_audio_config_format(struct sim_audio_s
*priv, snd_pcm_t *pcm)
priv->buffer_size = pframes * priv->frame_size;
priv->nbuffers = total_size / priv->buffer_size;
- ret = snd_pcm_hw_params_set_periods_near(pcm, hw_params,
- &priv->nbuffers, NULL);
+ ret = host_uninterruptible(snd_pcm_hw_params_set_periods_near, pcm,
+ hw_params, &priv->nbuffers, NULL);
if (ret < 0)
{
goto fail;
}
- ret = snd_pcm_hw_params(pcm, hw_params);
+ ret = host_uninterruptible(snd_pcm_hw_params, pcm, hw_params);
fail:
- snd_pcm_hw_params_free(hw_params);
+ host_uninterruptible_no_return(snd_pcm_hw_params_free, hw_params);
return ret;
}
@@ -249,7 +251,6 @@ static void sim_audio_config_ops(struct sim_audio_s *priv,
uint8_t fmt)
static int sim_audio_open(struct sim_audio_s *priv)
{
- irqstate_t flags;
snd_pcm_t *pcm = NULL;
int direction;
int ret;
@@ -259,15 +260,13 @@ static int sim_audio_open(struct sim_audio_s *priv)
return -ENXIO;
}
- flags = up_irq_save();
-
direction = priv->playback ? SND_PCM_STREAM_PLAYBACK
: SND_PCM_STREAM_CAPTURE;
- ret = snd_pcm_open(&pcm, "default", direction, 0);
+ ret = host_uninterruptible(snd_pcm_open, &pcm, "default", direction, 0);
if (ret < 0)
{
- goto fail;
+ return ret;
}
ret = sim_audio_config_format(priv, pcm);
@@ -276,7 +275,7 @@ static int sim_audio_open(struct sim_audio_s *priv)
goto fail;
}
- ret = snd_pcm_start(pcm);
+ ret = host_uninterruptible(snd_pcm_start, pcm);
if (ret < 0)
{
goto fail;
@@ -284,12 +283,12 @@ static int sim_audio_open(struct sim_audio_s *priv)
priv->pcm = pcm;
- up_irq_restore(flags);
return 0;
fail:
snd_pcm_close(pcm);
up_irq_restore(flags);
+ host_uninterruptible(snd_pcm_close, pcm);
return ret;
}
@@ -300,7 +299,7 @@ static int sim_audio_close(struct sim_audio_s *priv)
return -ENXIO;
}
- snd_pcm_close(priv->pcm);
+ host_uninterruptible(snd_pcm_close, priv->pcm);
priv->pcm = NULL;
@@ -380,15 +379,17 @@ static int sim_audio_getcaps(struct audio_lowerhalf_s
*dev, int type,
switch (caps->ac_format.hw)
{
case AUDIO_FU_VOLUME:
- snd_mixer_selem_get_playback_volume(priv->volume,
- SND_MIXER_SCHN_UNKNOWN,
- &val);
+ host_uninterruptible(snd_mixer_selem_get_playback_volume,
+ priv->volume,
+ SND_MIXER_SCHN_UNKNOWN,
+ &val);
caps->ac_controls.w = val;
break;
case AUDIO_FU_INP_GAIN:
- snd_mixer_selem_get_capture_volume(priv->volume,
- SND_MIXER_SCHN_MONO,
- &val);
+ host_uninterruptible(snd_mixer_selem_get_capture_volume,
+ priv->volume,
+ SND_MIXER_SCHN_MONO,
+ &val);
caps->ac_controls.w = val;
break;
default:
@@ -430,12 +431,14 @@ static int sim_audio_configure(struct audio_lowerhalf_s
*dev,
switch (caps->ac_format.hw)
{
case AUDIO_FU_VOLUME:
- ret = snd_mixer_selem_set_playback_volume_all(priv->volume,
- caps->ac_controls.hw[0]);
+ ret = host_uninterruptible(
+ snd_mixer_selem_set_playback_volume_all,
+ priv->volume, caps->ac_controls.hw[0]);
break;
case AUDIO_FU_INP_GAIN:
- ret = snd_mixer_selem_set_capture_volume_all(priv->volume,
- caps->ac_controls.hw[0]);
+ ret = host_uninterruptible(
+ snd_mixer_selem_set_capture_volume_all,
+ priv->volume, caps->ac_controls.hw[0]);
break;
default:
ret = -ENOTTY;
@@ -632,7 +635,7 @@ static int sim_alsa_get_latency(struct audio_lowerhalf_s
*dev,
return -ENXIO;
}
- ret = snd_pcm_delay(priv->pcm, latency);
+ ret = host_uninterruptible(snd_pcm_delay, priv->pcm, latency);
if (ret < 0)
{
return ret;
@@ -817,7 +820,8 @@ static int sim_audio_process_playback(struct sim_audio_s
*priv,
aux->curbyte += ret;
- ret = snd_pcm_writei(priv->pcm, out, outsize / priv->frame_size);
+ ret = host_uninterruptible(snd_pcm_writei, priv->pcm, out,
+ outsize / priv->frame_size);
ret *= priv->frame_size;
}
@@ -845,7 +849,8 @@ static int sim_audio_process_capture(struct sim_audio_s
*priv,
int frames = 0;
int ret;
- frames = snd_pcm_readi(priv->pcm, apb->samp, expect);
+ frames = host_uninterruptible(snd_pcm_readi, priv->pcm,
+ apb->samp, expect);
if (frames < 0)
{
return frames;
@@ -927,7 +932,7 @@ static void sim_audio_process(struct sim_audio_s *priv)
/ priv->frame_size;
}
- avail = snd_pcm_avail(priv->pcm);
+ avail = host_uninterruptible(snd_pcm_avail, priv->pcm);
if (avail < expect)
{
return;
@@ -973,7 +978,7 @@ static void sim_audio_process(struct sim_audio_s *priv)
if (final)
{
- snd_pcm_drain(priv->pcm);
+ host_uninterruptible(snd_pcm_drain, priv->pcm);
#ifdef CONFIG_AUDIO_MULTI_SESSION
sim_audio_stop(&priv->dev, NULL);
#else
@@ -988,46 +993,47 @@ out:
if (ret == -EPIPE)
{
awarn("ALSA buffer xrun.\n");
- snd_pcm_prepare(priv->pcm);
- snd_pcm_start(priv->pcm);
+ host_uninterruptible(snd_pcm_prepare, priv->pcm);
+ host_uninterruptible(snd_pcm_start, priv->pcm);
}
else if (ret != -EAGAIN)
{
- aerr("pcm writei/readi failed %d, %s\n", ret, snd_strerror(ret));
+ aerr("pcm writei/readi failed %d, %s\n", ret,
+ host_uninterruptible(snd_strerror, ret));
}
}
static int sim_mixer_open(struct sim_audio_s *priv)
{
snd_mixer_selem_id_t *sid = NULL;
- irqstate_t flags = up_irq_save();
int ret;
- ret = snd_mixer_open(&priv->mixer, 0);
+ ret = host_uninterruptible(snd_mixer_open, &priv->mixer, 0);
if (ret < 0)
{
goto fail;
}
- ret = snd_mixer_attach(priv->mixer, "default");
+ ret = host_uninterruptible(snd_mixer_attach, priv->mixer, "default");
if (ret < 0)
{
goto fail;
}
- ret = snd_mixer_selem_register(priv->mixer, NULL, NULL);
+ ret = host_uninterruptible(snd_mixer_selem_register,
+ priv->mixer, NULL, NULL);
if (ret < 0)
{
goto fail;
}
- ret = snd_mixer_load(priv->mixer);
+ ret = host_uninterruptible(snd_mixer_load, priv->mixer);
if (ret < 0)
{
goto fail;
}
- ret = snd_mixer_selem_id_malloc(&sid);
+ ret = host_uninterruptible(snd_mixer_selem_id_malloc, &sid);
if (ret < 0)
{
goto fail;
@@ -1035,17 +1041,20 @@ static int sim_mixer_open(struct sim_audio_s *priv)
if (priv->playback)
{
- snd_mixer_selem_id_set_index(sid, 0);
- snd_mixer_selem_id_set_name(sid, "Master");
+ host_uninterruptible_no_return(snd_mixer_selem_id_set_index, sid, 0);
+ host_uninterruptible_no_return(snd_mixer_selem_id_set_name,
+ sid, "Master");
- priv->volume = snd_mixer_find_selem(priv->mixer, sid);
- snd_mixer_selem_id_free(sid);
+ priv->volume = host_uninterruptible(snd_mixer_find_selem,
+ priv->mixer, sid);
+ host_uninterruptible_no_return(snd_mixer_selem_id_free, sid);
if (!priv->volume)
{
goto fail;
}
- ret = snd_mixer_selem_set_playback_volume_range(priv->volume, 0, 1000);
+ ret = host_uninterruptible(snd_mixer_selem_set_playback_volume_range,
+ priv->volume, 0, 1000);
if (ret < 0)
{
goto fail;
@@ -1053,28 +1062,29 @@ static int sim_mixer_open(struct sim_audio_s *priv)
}
else
{
- snd_mixer_selem_id_set_index(sid, 0);
- snd_mixer_selem_id_set_name(sid, "Capture");
+ host_uninterruptible_no_return(snd_mixer_selem_id_set_index, sid, 0);
+ host_uninterruptible_no_return(snd_mixer_selem_id_set_name,
+ sid, "Capture");
- priv->volume = snd_mixer_find_selem(priv->mixer, sid);
- snd_mixer_selem_id_free(sid);
+ priv->volume = host_uninterruptible(snd_mixer_find_selem,
+ priv->mixer, sid);
+ host_uninterruptible_no_return(snd_mixer_selem_id_free, sid);
if (!priv->volume)
{
goto fail;
}
- ret = snd_mixer_selem_set_capture_volume_range(priv->volume, 0, 1000);
+ ret = host_uninterruptible(snd_mixer_selem_set_capture_volume_range,
+ priv->volume, 0, 1000);
if (ret < 0)
{
goto fail;
}
}
- up_irq_restore(flags);
return 0;
fail:
- snd_mixer_close(priv->mixer);
- up_irq_restore(flags);
+ host_uninterruptible(snd_mixer_close, priv->mixer);
priv->mixer = NULL;
return 0;
}
diff --git a/arch/sim/src/sim/posix/sim_hostmemory.c
b/arch/sim/src/sim/posix/sim_hostmemory.c
index 3ba3adb97e..cc651cb46e 100644
--- a/arch/sim/src/sim/posix/sim_hostmemory.c
+++ b/arch/sim/src/sim/posix/sim_hostmemory.c
@@ -52,9 +52,6 @@ static atomic_int g_uordblks;
* Public Functions
****************************************************************************/
-extern uint64_t up_irq_save(void);
-extern void up_irq_restore(uint64_t flags);
-
/****************************************************************************
* Name: host_allocheap
*
@@ -65,21 +62,19 @@ extern void up_irq_restore(uint64_t flags);
void *host_allocheap(size_t sz)
{
- uint64_t flags = up_irq_save();
void *p;
#if defined(CONFIG_HOST_MACOS) && defined(CONFIG_HOST_ARM64)
/* see: https://developer.apple.com/forums/thread/672804 */
- p = mmap(NULL, sz, PROT_READ | PROT_WRITE,
- MAP_ANON | MAP_SHARED, -1, 0);
+ p = host_uninterruptible(mmap, NULL, sz, PROT_READ | PROT_WRITE,
+ MAP_ANON | MAP_SHARED, -1, 0);
#else
- p = mmap(NULL, sz, PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_ANON | MAP_PRIVATE, -1, 0);
+ p = host_uninterruptible(mmap, NULL, sz,
+ PROT_READ | PROT_WRITE | PROT_EXEC,
+ MAP_ANON | MAP_PRIVATE, -1, 0);
#endif
- up_irq_restore(flags);
-
if (p == MAP_FAILED)
{
return NULL;
@@ -98,14 +93,11 @@ void *host_allocheap(size_t sz)
void host_freeheap(void *mem)
{
- uint64_t flags = up_irq_save();
- munmap(mem, 0);
- up_irq_restore(flags);
+ host_uninterruptible(munmap, mem, 0);
}
void *host_allocshmem(const char *name, size_t size, int master)
{
- uint64_t flags = up_irq_save();
void *mem;
int oflag;
int ret;
@@ -117,10 +109,9 @@ void *host_allocshmem(const char *name, size_t size, int
master)
oflag |= O_CREAT | O_TRUNC;
}
- fd = shm_open(name, oflag, S_IRUSR | S_IWUSR);
+ fd = host_uninterruptible(shm_open, name, oflag, S_IRUSR | S_IWUSR);
if (fd < 0)
{
- up_irq_restore(flags);
return NULL;
}
@@ -128,20 +119,19 @@ void *host_allocshmem(const char *name, size_t size, int
master)
{
/* Avoid the second slave instance open successfully */
- shm_unlink(name);
+ host_uninterruptible(shm_unlink, name);
}
- ret = ftruncate(fd, size);
+ ret = host_uninterruptible(ftruncate, fd, size);
if (ret < 0)
{
- up_irq_restore(flags);
- close(fd);
+ host_uninterruptible(close, fd);
return NULL;
}
- mem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
- close(fd); /* Don't need keep fd any more once the memory get mapped */
- up_irq_restore(flags);
+ mem = host_uninterruptible(mmap, NULL, size,
+ PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ host_uninterruptible(close, fd); /* Don't need keep fd any more once the
memory get mapped */
if (mem == MAP_FAILED)
{
return NULL;
@@ -152,23 +142,20 @@ void *host_allocshmem(const char *name, size_t size, int
master)
void host_freeshmem(void *mem)
{
- uint64_t flags = up_irq_save();
- munmap(mem, 0);
- up_irq_restore(flags);
+ host_uninterruptible(munmap, mem, 0);
}
size_t host_mallocsize(void *mem)
{
#ifdef __APPLE__
- return malloc_size(mem);
+ return host_uninterruptible(malloc_size, mem);
#else
- return malloc_usable_size(mem);
+ return host_uninterruptible(malloc_usable_size, mem);
#endif
}
void *host_memalign(size_t alignment, size_t size)
{
- uint64_t flags = up_irq_save();
void *p;
int error;
@@ -177,18 +164,15 @@ void *host_memalign(size_t alignment, size_t size)
alignment = sizeof(void *);
}
- error = posix_memalign(&p, alignment, size);
+ error = host_uninterruptible(posix_memalign, &p, alignment, size);
if (error != 0)
{
- up_irq_restore(flags);
return NULL;
}
size = host_mallocsize(p);
- g_aordblks += 1;
- g_uordblks += size;
-
- up_irq_restore(flags);
+ atomic_fetch_add(&g_aordblks, 1);
+ atomic_fetch_add(&g_uordblks, size);
return p;
}
@@ -196,24 +180,20 @@ void *host_memalign(size_t alignment, size_t size)
void host_free(void *mem)
{
size_t size;
- uint64_t flags;
if (mem == NULL)
{
return;
}
- flags = up_irq_save();
size = host_mallocsize(mem);
- g_aordblks -= 1;
- g_uordblks -= size;
- free(mem);
- up_irq_restore(flags);
+ atomic_fetch_sub(&g_aordblks, 1);
+ atomic_fetch_sub(&g_uordblks, size);
+ host_uninterruptible_no_return(free, mem);
}
void *host_realloc(void *oldmem, size_t size)
{
- uint64_t flags;
size_t oldsize;
void *mem;
@@ -222,27 +202,21 @@ void *host_realloc(void *oldmem, size_t size)
return host_memalign(sizeof(void *), size);
}
- flags = up_irq_save();
-
oldsize = host_mallocsize(oldmem);
- mem = realloc(oldmem, size);
+ mem = host_uninterruptible(realloc, oldmem, size);
if (mem == NULL)
{
- up_irq_restore(flags);
return NULL;
}
size = host_mallocsize(mem);
- g_uordblks -= oldsize;
- g_uordblks += size;
-
- up_irq_restore(flags);
+ atomic_fetch_add(&g_uordblks, size - oldsize);
return mem;
}
void host_mallinfo(int *aordblks, int *uordblks)
{
- *aordblks = g_aordblks;
- *uordblks = g_uordblks;
+ *aordblks = atomic_load(&g_aordblks);
+ *uordblks = atomic_load(&g_uordblks);
}
diff --git a/arch/sim/src/sim/posix/sim_hostmisc.c
b/arch/sim/src/sim/posix/sim_hostmisc.c
index b23403c24c..a1856b8d47 100644
--- a/arch/sim/src/sim/posix/sim_hostmisc.c
+++ b/arch/sim/src/sim/posix/sim_hostmisc.c
@@ -52,8 +52,6 @@ void __gcov_dump(void);
* Public Functions
****************************************************************************/
-extern uint64_t up_irq_save(void);
-extern void up_irq_restore(uint64_t flags);
extern int backtrace(void **array, int size);
/****************************************************************************
@@ -68,19 +66,15 @@ extern int backtrace(void **array, int size);
void host_abort(int status)
{
- uint64_t flags = up_irq_save();
-
#ifdef CONFIG_ARCH_COVERAGE
/* Dump gcov data. */
- __gcov_dump();
+ host_uninterruptible_no_return(__gcov_dump);
#endif
/* exit the simulation */
- exit(status);
-
- up_irq_restore(flags);
+ host_uninterruptible_no_return(exit, status);
}
/****************************************************************************
@@ -99,13 +93,7 @@ int host_backtrace(void** array, int size)
#ifdef CONFIG_WINDOWS_CYGWIN
return 0;
#else
- uint64_t flags = up_irq_save();
- int ret;
-
- ret = backtrace(array, size);
-
- up_irq_restore(flags);
- return ret;
+ return host_uninterruptible(backtrace, array, size);
#endif
}
@@ -130,7 +118,6 @@ int host_system(char *buf, size_t len, const char *fmt, ...)
{
FILE *fp;
int ret;
- uint64_t flags;
char cmd[512];
va_list vars;
@@ -144,21 +131,18 @@ int host_system(char *buf, size_t len, const char *fmt,
...)
if (buf == NULL)
{
- ret = system(cmd);
+ ret = host_uninterruptible(system, cmd);
}
else
{
- flags = up_irq_save();
- fp = popen(cmd, "r");
+ fp = host_uninterruptible(popen, cmd, "r");
if (fp == NULL)
{
- up_irq_restore(flags);
return -errno;
}
- ret = fread(buf, sizeof(char), len, fp);
- pclose(fp);
- up_irq_restore(flags);
+ ret = host_uninterruptible(fread, buf, 1, len, fp);
+ host_uninterruptible(pclose, fp);
}
return ret < 0 ? -errno : ret;
@@ -178,10 +162,10 @@ void host_init_cwd(void)
/* Get the absolute path of the executable file */
# ifdef CONFIG_HOST_LINUX
- len = readlink("/proc/self/exe", path, len);
+ len = host_uninterruptible(readlink, "/proc/self/exe", path, len);
if (len < 0)
{
- perror("readlink failed");
+ host_uninterruptible_no_return(perror, "readlink failed");
return;
}
# else
@@ -195,7 +179,7 @@ void host_init_cwd(void)
path[len] = '\0';
name = strrchr(path, '/');
*++name = '\0';
- chdir(path);
+ host_uninterruptible(chdir, path);
}
#endif
@@ -218,7 +202,8 @@ pid_t host_posix_spawn(const char *path,
argv = default_argv;
}
- ret = posix_spawn(&pid, path, NULL, NULL, argv, envp);
+ ret = host_uninterruptible(posix_spawn, &pid, path,
+ NULL, NULL, argv, envp);
return ret > 0 ? -ret : pid;
}
@@ -230,6 +215,6 @@ int host_waitpid(pid_t pid)
{
int status;
- pid = waitpid(pid, &status, 0);
+ pid = host_uninterruptible(waitpid, pid, &status, 0);
return pid < 0 ? -errno : status;
}
diff --git a/arch/sim/src/sim/sim_internal.h b/arch/sim/src/sim/sim_internal.h
index c62b78d538..0364514614 100644
--- a/arch/sim/src/sim/sim_internal.h
+++ b/arch/sim/src/sim/sim_internal.h
@@ -120,6 +120,27 @@
} \
while (0)
+#define host_uninterruptible(func, ...) \
+ ({ \
+ extern uint64_t up_irq_save(void); \
+ extern void up_irq_restore(uint64_t flags); \
+ uint64_t flags_ = up_irq_save(); \
+ typeof(func(__VA_ARGS__)) ret_ = func(__VA_ARGS__); \
+ up_irq_restore(flags_); \
+ ret_; \
+ })
+
+#define host_uninterruptible_no_return(func, ...) \
+ do \
+ { \
+ extern uint64_t up_irq_save(void); \
+ extern void up_irq_restore(uint64_t flags); \
+ uint64_t flags_ = up_irq_save(); \
+ func(__VA_ARGS__); \
+ up_irq_restore(flags_); \
+ } \
+ while (0)
+
/* File System Definitions **************************************************/
/* These definitions characterize the compressed filesystem image */
