[PATCH] selftest: size: Add size test for Linux kernel

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

Signed-off-by: Tim Bird <redacted>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 45f145c..fa91aef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile

@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug

diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..51e5fbd
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile

@@ -0,0 +1,21 @@
+#ifndef CC
+	CC = $(CROSS_COMPILE)gcc
+#endif
+
+#ifndef STRIP
+	STRIP = $(CROSS_COMPILE)strip
+#endif
+
+all: get_size
+
+get_size: get_size.c
+	$(CC) --static -ffreestanding -nostartfiles \
+		-Wl,--entry=main get_size.c -o get_size \
+		`cc -print-libgcc-file-name`
+	$(STRIP) -s get_size
+
+run_tests: all
+	./get_size
+
+clean:
+	$(RM) get_size

diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
new file mode 100644
index 0000000..f8ffc80
--- /dev/null
+++ b/tools/testing/selftests/size/get_size.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2014 Sony
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftest for runtime system size
+ *
+ * Prints the amount of RAM that the currently running system is using.
+ *
+ * This program tries to be as small as possible itself, to
+ * avoid perturbing the system memory utilization with its
+ * own execution.  It also attempts to have as few dependencies
+ * on kernel features as possible.
+ *
+ * It should be statically linked, with startup libs avoided.
+ * It uses no library calls, and only the following 3 syscalls:
+ *   sysinfo(), write(), and _exit()
+ *
+ * For output, it avoids printf (which in some C libraries
+ * has large external dependencies) by implementing its own
+ * strlen(), number output and print() routines.
+ */
+
+#include <sys/sysinfo.h>
+#include <unistd.h>
+
+#define STDOUT_FILENO 1
+
+my_strlen(const char *s)
+{
+	int len = 0;
+
+	while (*s++)
+		len++;
+	return len;
+}
+
+/*
+ * num_to_str - put digits from num into *s, left to right
+ *   do this by dividing the number by powers of 10
+ *   the tricky part is to omit leading zeros
+ *   don't print zeros until we've started printing any numbers at all
+ */
+static void num_to_str(unsigned long num, char *s)
+{
+	unsigned long long temp, div;
+	int started;
+
+	temp = num;
+	div = 1000000000000000000LL;
+	started = 0;
+	while (div) {
+		if (temp/div || started) {
+			*s++ = (unsigned char)(temp/div + '0');
+			started = 1;
+		}
+		temp -= (temp/div)*div;
+		div /= 10;
+	}
+	*s = 0;
+}
+
+print_num(unsigned long num)
+{
+	char num_buf[30];
+
+	num_to_str(num, num_buf);
+	write(STDOUT_FILENO, num_buf, my_strlen(num_buf));
+}
+
+print(char *s)
+{
+	write(STDOUT_FILENO, s, my_strlen(s));
+}
+
+void main(int argc, char **argv)
+{
+	int ccode;
+	unsigned long used;
+	struct sysinfo info;
+	unsigned long long temp;
+
+	print("Testing system size.\n");
+	print("1..1\n");
+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get size runtime size\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+
+	/* ignore cache complexities for now */
+	temp = info.totalram - info.freeram - info.bufferram;
+	temp = temp * info.mem_unit;
+	temp = temp / 1024;
+
+	used = temp;
+
+	print("ok 1 get runtime size # size = ");
+	print_num(used);
+	print(" K\n");
+
+	_exit(0);
+}

-- 
1.8.2.2

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 45f145c..fa91aef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile

@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug

diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..51e5fbd
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile

@@ -0,0 +1,21 @@
+#ifndef CC
+	CC = $(CROSS_COMPILE)gcc
+#endif
+
+#ifndef STRIP
+	STRIP = $(CROSS_COMPILE)strip
+#endif
+
+all: get_size
+
+get_size: get_size.c
+	$(CC) --static -ffreestanding -nostartfiles \
+		-Wl,--entry=main get_size.c -o get_size \
+		`cc -print-libgcc-file-name`
+	$(STRIP) -s get_size
+
+run_tests: all
+	./get_size
+
+clean:
+	$(RM) get_size

diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
new file mode 100644
index 0000000..f8ffc80
--- /dev/null
+++ b/tools/testing/selftests/size/get_size.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2014 Sony Mobile Communications Inc.
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftest for runtime system size
+ *
+ * Prints the amount of RAM that the currently running system is using.
+ *
+ * This program tries to be as small as possible itself, to
+ * avoid perturbing the system memory utilization with its
+ * own execution.  It also attempts to have as few dependencies
+ * on kernel features as possible.
+ *
+ * It should be statically linked, with startup libs avoided.
+ * It uses no library calls, and only the following 3 syscalls:
+ *   sysinfo(), write(), and _exit()
+ *
+ * For output, it avoids printf (which in some C libraries
+ * has large external dependencies) by implementing its own
+ * strlen(), number output and print() routines.
+ */
+
+#include <sys/sysinfo.h>
+#include <unistd.h>
+
+#define STDOUT_FILENO 1
+
+my_strlen(const char *s)
+{
+	int len = 0;
+
+	while (*s++)
+		len++;
+	return len;
+}
+
+/*
+ * num_to_str - put digits from num into *s, left to right
+ *   do this by dividing the number by powers of 10
+ *   the tricky part is to omit leading zeros
+ *   don't print zeros until we've started printing any numbers at all
+ */
+static void num_to_str(unsigned long num, char *s)
+{
+	unsigned long long temp, div;
+	int started;
+
+	temp = num;
+	div = 1000000000000000000LL;
+	started = 0;
+	while (div) {
+		if (temp/div || started) {
+			*s++ = (unsigned char)(temp/div + '0');
+			started = 1;
+		}
+		temp -= (temp/div)*div;
+		div /= 10;
+	}
+	*s = 0;
+}
+
+print_num(unsigned long num)
+{
+	char num_buf[30];
+
+	num_to_str(num, num_buf);
+	write(STDOUT_FILENO, num_buf, my_strlen(num_buf));
+}
+
+print(char *s)
+{
+	write(STDOUT_FILENO, s, my_strlen(s));
+}
+
+void main(int argc, char **argv)
+{
+	int ccode;
+	unsigned long used;
+	struct sysinfo info;
+	unsigned long long temp;
+
+	print("Testing system size.\n");
+	print("1..1\n");
+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get size runtime size\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+
+	/* ignore cache complexities for now */
+	temp = info.totalram - info.freeram - info.bufferram;
+	temp = temp * info.mem_unit;
+	temp = temp / 1024;
+
+	used = temp;
+
+	print("ok 1 get runtime size # size = ");
+	print_num(used);
+	print(" K\n");
+
+	_exit(0);
+}

-- 
1.8.2.2

On 11/19/2014 05:13 PM, Tim Bird wrote:

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

Tim,

The test looks good, but you are missing .gitignore file.
Please add a .gitignore for the binary that gets generated to
avoid git status including the binary it in its output.

thanks,
-- Shuah


-- 
Shuah Khan
Sr. Linux Kernel Developer
Samsung Research America (Silicon Valley)
shuahkh-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org | (970) 217-8978

On 11/20/2014 01:58 PM, Shuah Khan wrote:

On 11/19/2014 05:13 PM, Tim Bird wrote:

quoted

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

Tim,

The test looks good, but you are missing .gitignore file.
Please add a .gitignore for the binary that gets generated to
avoid git status including the binary it in its output.

Will do.

I'll send v3 today.

Thanks,
 -- Tim

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

Changes from v2:
  - add return values to print routines
  - add .gitignore file

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---
 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/.gitignore |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 4 files changed, 128 insertions(+)
 create mode 100644 tools/testing/selftests/size/.gitignore
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 45f145c..fa91aef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile

@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug

diff --git a/tools/testing/selftests/size/.gitignore b/tools/testing/selftests/size/.gitignore
new file mode 100644
index 0000000..189b781
--- /dev/null
+++ b/tools/testing/selftests/size/.gitignore

@@ -0,0 +1 @@
+get_size

diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..51e5fbd
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile

@@ -0,0 +1,21 @@
+#ifndef CC
+	CC = $(CROSS_COMPILE)gcc
+#endif
+
+#ifndef STRIP
+	STRIP = $(CROSS_COMPILE)strip
+#endif
+
+all: get_size
+
+get_size: get_size.c
+	$(CC) --static -ffreestanding -nostartfiles \
+		-Wl,--entry=main get_size.c -o get_size \
+		`cc -print-libgcc-file-name`
+	$(STRIP) -s get_size
+
+run_tests: all
+	./get_size
+
+clean:
+	$(RM) get_size

diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
new file mode 100644
index 0000000..9c8d3cd
--- /dev/null
+++ b/tools/testing/selftests/size/get_size.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2014 Sony
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftest for runtime system size
+ *
+ * Prints the amount of RAM that the currently running system is using.
+ *
+ * This program tries to be as small as possible itself, to
+ * avoid perturbing the system memory utilization with its
+ * own execution.  It also attempts to have as few dependencies
+ * on kernel features as possible.
+ *
+ * It should be statically linked, with startup libs avoided.
+ * It uses no library calls, and only the following 3 syscalls:
+ *   sysinfo(), write(), and _exit()
+ *
+ * For output, it avoids printf (which in some C libraries
+ * has large external dependencies) by implementing its own
+ * strlen(), number output and print() routines.
+ */
+
+#include <sys/sysinfo.h>
+#include <unistd.h>
+
+#define STDOUT_FILENO 1
+
+int my_strlen(const char *s)
+{
+	int len = 0;
+
+	while (*s++)
+		len++;
+	return len;
+}
+
+/*
+ * num_to_str - put digits from num into *s, left to right
+ *   do this by dividing the number by powers of 10
+ *   the tricky part is to omit leading zeros
+ *   don't print zeros until we've started printing any numbers at all
+ */
+void num_to_str(unsigned long num, char *s)
+{
+	unsigned long long temp, div;
+	int started;
+
+	temp = num;
+	div = 1000000000000000000LL;
+	started = 0;
+	while (div) {
+		if (temp/div || started) {
+			*s++ = (unsigned char)(temp/div + '0');
+			started = 1;
+		}
+		temp -= (temp/div)*div;
+		div /= 10;
+	}
+	*s = 0;
+}
+
+int print_num(unsigned long num)
+{
+	char num_buf[30];
+
+	num_to_str(num, num_buf);
+	return write(STDOUT_FILENO, num_buf, my_strlen(num_buf));
+}
+
+int print(char *s)
+{
+	return write(STDOUT_FILENO, s, my_strlen(s));
+}
+
+void main(int argc, char **argv)
+{
+	int ccode;
+	unsigned long used;
+	struct sysinfo info;
+	unsigned long long temp;
+
+	print("Testing system size.\n");
+	print("1..1\n");
+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get size runtime size\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+
+	/* ignore cache complexities for now */
+	temp = info.totalram - info.freeram - info.bufferram;
+	temp = temp * info.mem_unit;
+	temp = temp / 1024;
+
+	used = temp;
+
+	print("ok 1 get runtime size # size = ");
+	print_num(used);
+	print(" K\n");
+
+	_exit(0);
+}

-- 
1.8.2.2

On 11/24/2014 11:20 AM, Tim Bird wrote:

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

This following version information shouldn't be part of changelog.

Changes from v2:
  - add return values to print routines
  - add .gitignore file

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---

Goes here.

I ran this test and the reporting could be improved.
Could you change the above to say

System RAM in use instead of system size. Also can you also
print total RAM and other information you already have:

Maybe something along the lines of:

System RAM report (units Kilobytes):
   Total:
   Free:
   Bufferram:
   In use:

I would remove the print("1..1\n");

+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get size runtime size\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+
+	/* ignore cache complexities for now */
+	temp = info.totalram - info.freeram - info.bufferram;
+	temp = temp * info.mem_unit;
+	temp = temp / 1024;
+
+	used = temp;
+
+	print("ok 1 get runtime size # size = ");
+	print_num(used);
+	print(" K\n");

Please see above. You can get rid of print(" K\n"); at the end.

Sorry for not giving this feedback earlier. The not so clear
reporting aspect stood out for me after running the test.

thanks,
-- Shuah

-- 
Shuah Khan
Sr. Linux Kernel Developer
Samsung Research America (Silicon Valley)
shuahkh-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org | (970) 217-8978

On 11/25/2014 12:39 PM, Shuah Khan wrote:

On 11/24/2014 11:20 AM, Tim Bird wrote:

quoted

This test shows the amount of memory used by the system.
Note that this is dependent on the user-space that is loaded
when this program runs.  Optimally, this program would be
run as the init program itself.

The program is optimized for size itself, to avoid conflating
its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system,
this results in a statically linked binary of less than 5K.

This following version information shouldn't be part of changelog.

quoted

Changes from v2:
  - add return values to print routines
  - add .gitignore file

Changes from v1:
  - use more correct Copyright string in get_size.c

Signed-off-by: Tim Bird <tim.bird-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
---

Goes here.

OK - I'll change this.

quoted

 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/.gitignore |   1 +
 tools/testing/selftests/size/Makefile   |  21 +++++++
 tools/testing/selftests/size/get_size.c | 105 ++++++++++++++++++++++++++++++++
 4 files changed, 128 insertions(+)
 create mode 100644 tools/testing/selftests/size/.gitignore
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 45f145c..fa91aef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile

@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug

diff --git a/tools/testing/selftests/size/.gitignore b/tools/testing/selftests/size/.gitignore
new file mode 100644
index 0000000..189b781
--- /dev/null
+++ b/tools/testing/selftests/size/.gitignore

@@ -0,0 +1 @@
+get_size

diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..51e5fbd
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile

@@ -0,0 +1,21 @@
+#ifndef CC
+	CC = $(CROSS_COMPILE)gcc
+#endif
+
+#ifndef STRIP
+	STRIP = $(CROSS_COMPILE)strip
+#endif
+
+all: get_size
+
+get_size: get_size.c
+	$(CC) --static -ffreestanding -nostartfiles \
+		-Wl,--entry=main get_size.c -o get_size \
+		`cc -print-libgcc-file-name`
+	$(STRIP) -s get_size
+
+run_tests: all
+	./get_size
+
+clean:
+	$(RM) get_size

diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
new file mode 100644
index 0000000..9c8d3cd
--- /dev/null
+++ b/tools/testing/selftests/size/get_size.c

@@ -0,0 +1,105 @@
+/*
+ * Copyright 2014 Sony
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftest for runtime system size
+ *
+ * Prints the amount of RAM that the currently running system is using.
+ *
+ * This program tries to be as small as possible itself, to
+ * avoid perturbing the system memory utilization with its
+ * own execution.  It also attempts to have as few dependencies
+ * on kernel features as possible.
+ *
+ * It should be statically linked, with startup libs avoided.
+ * It uses no library calls, and only the following 3 syscalls:
+ *   sysinfo(), write(), and _exit()
+ *
+ * For output, it avoids printf (which in some C libraries
+ * has large external dependencies) by implementing its own
+ * strlen(), number output and print() routines.
+ */
+
+#include <sys/sysinfo.h>
+#include <unistd.h>
+
+#define STDOUT_FILENO 1
+
+int my_strlen(const char *s)
+{
+	int len = 0;
+
+	while (*s++)
+		len++;
+	return len;
+}
+
+/*
+ * num_to_str - put digits from num into *s, left to right
+ *   do this by dividing the number by powers of 10
+ *   the tricky part is to omit leading zeros
+ *   don't print zeros until we've started printing any numbers at all
+ */
+void num_to_str(unsigned long num, char *s)
+{
+	unsigned long long temp, div;
+	int started;
+
+	temp = num;
+	div = 1000000000000000000LL;
+	started = 0;
+	while (div) {
+		if (temp/div || started) {
+			*s++ = (unsigned char)(temp/div + '0');
+			started = 1;
+		}
+		temp -= (temp/div)*div;
+		div /= 10;
+	}
+	*s = 0;
+}
+
+int print_num(unsigned long num)
+{
+	char num_buf[30];
+
+	num_to_str(num, num_buf);
+	return write(STDOUT_FILENO, num_buf, my_strlen(num_buf));
+}
+
+int print(char *s)
+{
+	return write(STDOUT_FILENO, s, my_strlen(s));
+}
+
+void main(int argc, char **argv)
+{
+	int ccode;
+	unsigned long used;
+	struct sysinfo info;
+	unsigned long long temp;
+
+	print("Testing system size.\n");
+	print("1..1\n");

I ran this test and the reporting could be improved.
Could you change the above to say

System RAM in use instead of system size.

I'll have to think about this.  I'm not sure what the
correct phrasing would be for XIP systems (for which part of
the kernel resides in flash, not RAM, maybe "memory"?)

Also can you also
print total RAM and other information you already have:

I can print it as part of total output, but for regression
testing and automation I want the tool to have a single
number result as output (well, one number relating to runtime
size, and I'm considering adding one number relating
to compile-time size.)

Maybe something along the lines of:

System RAM report (units Kilobytes):
   Total:
   Free:
   Bufferram:
   In use:

I would remove the print("1..1\n");

This is part of the TAP output format.

Is there any (other) output format being standardized for selftest
programs?

TAP allows me to output more human-readable information to go
along with the "official" result, but I'd like to keep the
official result in TAP format so it can be handled by automated
tools.  Maybe it would be best to output both.

I'll try to make a counter-proposal tomorrow that we can discus.

quoted

+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get size runtime size\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+
+	/* ignore cache complexities for now */
+	temp = info.totalram - info.freeram - info.bufferram;
+	temp = temp * info.mem_unit;
+	temp = temp / 1024;
+
+	used = temp;
+
+	print("ok 1 get runtime size # size = ");
+	print_num(used);
+	print(" K\n");

Please see above. You can get rid of print(" K\n"); at the end.

Sorry for not giving this feedback earlier. The not so clear
reporting aspect stood out for me after running the test.

No problem.  Thanks for looking at it.
I have some additional changes, based on feedback from Josh Triplett,
so look for a v4 tomorrow.

 -- Tim