I'm studying Operating Systems and, of course, Minix 3. Can someone tell me which file and line of code in Minix 3 are the entry points of:
Any of above will help me a lot.
Thanks.
I'm using the main github source: https://github.com/Stichting-MINIX-Research-Foundation/minix
Try first searching for the device drivers since they are more "self-contained". Device drivers are found inhttps://github.com/Stichting-MINIX-Research-Foundation/minix/tree/master/minix/drivers
Instead of just pointing the entry points, I will show how I usually do. I will use the minix/drivers/video/fb/fb.h as an example. The fb is a driver responsible for controlling video displayed on a monitor. I could open any file, but I chose the fb.h since it is a header file and will contain the signatures of public functions.
I am on Linux so I can use the grep -r command. The -r flag search recursively for the given pattern. So by inspecting fb.h I found the following functions:
int arch_fb_init(int minor, struct edid_info *info);
int arch_get_device(int minor, struct device *dev);
int arch_get_varscreeninfo(int minor, struct fb_var_screeninfo *fbvsp);
int arch_put_varscreeninfo(int minor, struct fb_var_screeninfo *fbvs_copy);
int arch_get_fixscreeninfo(int minor, struct fb_fix_screeninfo *fbfsp);
int arch_pan_display(int minor, struct fb_var_screeninfo *fbvs_copy);
Well, arch_fb_init seems to be an entry point. To verify if arch_fb_init is indeed an entry point, I use
grep -r "arch_fb_init"
Which in turn returns the following
$ grep -r "arch_fb_init"
drivers/video/fb/arch/earm/fb_arch.c:arch_fb_init(int minor, struct edid_info *info)
drivers/video/fb/fb.h:int arch_fb_init(int minor, struct edid_info *info);
drivers/video/fb/fb.c: if (arch_fb_init(minor, infop) == OK) {
The second match is the fb.h itself. The other two are in fb_arch.c and fb.c. Then I go to those files and inspect each of them. Opening fb_arch.c and searching for arch_fb_init I find on line 315 an implementation of this function. By now, the implementation of the function could be more interesting because we want to figure out the caller/callee hierarchy.
Opening fb.c I find an occurrence of arch_fb_init on line 74, which is a call to arch_fb_init. This call to arch_fb_init is performed by another function named fb_open (line 60 on fb.c).
Now I repeat the process but now searching for fb_open. Performing another grep now returns the following.
$ grep -r "fb_open"
drivers/video/fb/fb.c:static int fb_open(devminor_t minor, int access, endpoint_t user_endpt);
drivers/video/fb/fb.c: .cdr_open = fb_open,
drivers/video/fb/fb.c:fb_open(devminor_t minor, int UNUSED(access), endpoint_t UNUSED(user_endpt))
All the occurrences are also in fb.c. By inspecting fb.c, one can see that the first grep match is a declaration of the fb_open function, and the third one is the implementation itself. The second one is using fb_open to construct a table (line 46 on file fb.c) that you can see below
/* Entry points to the fb driver. */
static struct chardriver fb_tab =
{
.cdr_open = fb_open,
.cdr_close = fb_close,
.cdr_read = fb_read,
.cdr_write = fb_write,
.cdr_ioctl = fb_ioctl
};
The commentary "Entry points to the fb driver." indicates that we are getting closer. If you have an IDE capable of parsing the Minix project, it will be easier to find all the callers/callee. If you don't have an IDE, you can use the grep command with the -r flag. If you know object orientation, this fb_tab is kind of a virtual table. Probably is setting callbacks that the kernel can use when calling this driver. I'm not sure because I never worked with minix before, but I have some general knowledge in OS, and the names used imply that I may be right.
Now searching for fb_tab by using grep, I get the following:
$ grep -r "fb_tab"
drivers/video/fb/fb.c:static struct chardriver fb_tab =
drivers/video/fb/fb.c: chardriver_task(&fb_tab);
All the occurrences once again in fb.c. The first match is the definition of fb_tab itself. The second one is the following
int
main(int argc, char *argv[])
{
env_setargs(argc, argv);
fb_edid_args_parse();
sef_local_startup();
chardriver_task(&fb_tab);
return OK;
}
By inspecting this main function, env_setargs and fb_edid_args_parse are probably just parsing arguments and setting flags. Now, the sef_local_startup and chardriver_task functions may be worth performing a grep.
Performing a grep on chardriver_task returns the following:
$ grep -r "chardriver_task"
drivers/examples/hello/hello.c: chardriver_task(&hello_tab);
drivers/sensors/tsl2550/tsl2550.c: chardriver_task(&tsl2550_tab);
drivers/sensors/bmp085/bmp085.c: chardriver_task(&bmp085_tab);
drivers/sensors/sht21/sht21.c: chardriver_task(&sht21_tab);
drivers/printer/printer/printer.c: chardriver_task(&printer_tab);
drivers/system/log/log.c: chardriver_task(&log_dtab);
drivers/system/random/main.c: chardriver_task(&r_dtab);
drivers/bus/i2c/i2c.c: chardriver_task(&i2c_tab);
drivers/bus/pci/main.c: chardriver_task(&driver);
drivers/video/fb/fb.c: chardriver_task(&fb_tab);
include/minix/chardriver.h:void chardriver_task(const struct chardriver *cdp);
servers/input/input.c: chardriver_task(&input_tab);
lib/libchardriver/chardriver.c: * chardriver_task *
lib/libchardriver/chardriver.c:void chardriver_task(const struct chardriver *cdp)
lib/libaudiodriver/audio_fw.c: chardriver_task(&audio_tab);
Many of the matches are calling the chardriver_task similar to the one found in fb.c but the following probably is the declaration
include/minix/chardriver.h:void chardriver_task(const struct chardriver *cdp);
And this one probably is the implementation
lib/libchardriver/chardriver.c:void chardriver_task(const struct chardriver *cdp)
As you can see, there isn't a clear entry point. It depends on what you're searching for. In the case of the fb driver, if you're searching for its initialization, it is probably the main function. However, if you're searching for how the kernel will be calling the driver probably is by the callbacks set on fb_tab.
If you can edit your question, someone will probably give you a better answer.
