OS: Mengerti System Call - Revision history

Onnowpurbo: /* Pranala Menarik */

2013-04-07T06:44:15Z

Pranala Menarik

Onnowpurbo: /* Pranala Menarik */

2013-04-03T06:04:41Z

Pranala Menarik

Onnowpurbo: /* Contoh System Call */

2013-04-02T04:07:51Z

Contoh System Call

Onnowpurbo: /* Contoh System Call */

2013-04-02T03:55:40Z

Contoh System Call

Onnowpurbo: /* Contoh System Call */

2013-04-02T03:36:16Z

Contoh System Call

Onnowpurbo: /* Contoh System Call */

2013-04-02T03:30:34Z

Contoh System Call

Onnowpurbo: /* Lebih detail tentang System call */

2013-04-02T03:25:21Z

Lebih detail tentang System call

Onnowpurbo at 03:16, 2 April 2013

2013-04-02T03:16:35Z

Onnowpurbo: /* A system call example */

2013-04-02T02:57:06Z

A system call example

Onnowpurbo: /* Lebih detail tentang System call */

2013-04-02T02:27:08Z

Lebih detail tentang System call

@@ Line 100: / Line 100: @@
 * [[Linux]]
 * [[Ubuntu]]
 * [[Linux: CLI untuk Survival]]
-* [[Sistem Operasi]]
+* [[Linux: Skema Partisi di Linux]]
 * [[Linux: Instalasi Sistem Operasi]]
-* [[Linux: Skema Partisi di Linux]]
 * [[Kernel]]
 * [[Compile Kernel]]
 * [[Compile Kernel: Konfigurasi Kernel]]
-* [[Kernel: Anatomi Kernel Source]]
-* [[OS: Linux Kernel]]
+===Remaster Linux===
 * [[OS: Parameter Kernel Default]]
 * [[OS: Kernel Scheduler]]
 * [[OS: Complete Teori Tuning Kernel Scheduler]]
 * [[OS: Complete Teori Tuning I/O Performance]]
 * [[OS: Tuning Manajemen Memory]]
-* [[OS: Tuning Kernel Scheduler]]
-* [[OS: Tuning Completely Fair Queueing CFQ I/O scheduler]]
+===Android===
-* [[OS: Tuning Completely Fair scheduler CFS]]
 * [[OS: Build in Monitoring Tool]]
 * [[Linux Benchmarking]]
 * [[OS: Benchmarking menggunakan UnixBench]]
 * [[OS: Benchmarking menggunakan LLCBench]]

@@ Line 100: / Line 100: @@
 * [[Linux]]
 * [[Ubuntu]]
 * [[Sistem Operasi]]
 * [[Kernel]]
 * [[Compile Kernel]]
@@ Line 110: / Line 113: @@
 * [[OS: Complete Teori Tuning Kernel Scheduler]]
 * [[OS: Complete Teori Tuning I/O Performance]]
 * [[OS: Tuning Kernel Scheduler]]
 * [[OS: Tuning Completely Fair Queueing CFQ I/O scheduler]]
@@ Line 119: / Line 123: @@
 * [[OS: Mengerti System Call]]
 * [[OS: Membuat Kernel Modul]]

@@ Line 75: / Line 75: @@
 '''fs/read_write.c'''
-This function finds the file struct associated with the fd number you passed to the read() function. That structure contains a pointer to the function that should be used to read data from that particular kind of file. After doing some checks, it calls that file-specific read function in order to actually read the data from the file, and then returns. This file-specific function is defined somewhere else - the socket code, filesystem code, or device driver code, for example. This is one of the points at which a specific kernel subsystem finally interfaces with the rest of the kernel. After our read function finishes, we return from the sys_read(), back to DoSyscall(), which switches control to ret_from_except, which is in defined in:
+Function ini akan mengambil fice struct yang berhubungan dengan nomor fd yang kita kirim ke function read(). Struct ini berisi pointer ke function yang harusnya digunakan untuk membaca data dari file tertentu. Setelah melakukan beberapa check, dia akan call function read untuk file tertentu untuk membaca data dari file, dan kemudian return. Function file spesifik ini di definisikan di tempat lain, contohnya,socket code, file system code, atau device driver code. Di titik ini, sebuah subsystem kernel yang spesifik akan berinteraksi dengan kernel secara keseluruhan. Setelah function read kita selesai, kita akan kembali dari sys_read(), kembali ke DoSyscall(), akan akan men-switch control ret_from_except, yang di definisikan di:
 '''arch/ppc/kernel/entry.S'''
-This checks for tasks that might need to be done before switching back to user mode. If nothing else needs to be done, we fall through to the restore function, which restores the user process's state and returns control back to the user program. There! Your read() call is done! If you're lucky, you even got your data back.
+Di tempat sini akan di cek task yang perlu diselesaikan sebelum switch kembali ke user mode. Jika tidak ada lagi yang perlu dilakukan, kita akan kembali ke function restore, yang akan me-restore state user proses dan mengembalikan control ke user program. Selesai sudah call ke read(). Jika kita beruntung, kita akan memperoleh data kita kembali.
-You can explore syscalls further by putting printks at strategic places. Be sure to limit the amount of output from these printks. For example, if you add a printk to sys_read() syscall, you should do something like this:
+Kita dapat mengeksplorasi syscall lebih dalam lagi dengan menempatkan printk pada berbagai tempat yang strategis. Pastikan untuk memberi batasan jumlah output dari printk, Contoh, kita dapat menambahkan printk ke syscall sys_read(), kita dapat menambahkan sebagai berikut:
   static int mycount = 0;
@@ Line 90: / Line 90: @@
+    }
-Have fun!
+Selamat menikmati!
 ==Referensi==

@@ Line 71: / Line 71: @@
 Tabel syscall berisi address dari function yang mengimplementasikan setiap system call. Contoh, function system call read() bernama sys_read. Nomor system call read() adalah 3, oleh karenanya address dari sys_read() adalah entry ke 4 di tabel system call (karena nomor pertama system call adalah 0). Kita membaca data dari address sys_call_table + (3 * word_size) dan kita akan memperoleh address dari sys_read().
-After DoSyscall has looked up the correct system call address, it transfers control to that system call. Let's look at where sys_read() is defined, in the file:
+Setelah DoSyscall diperoleh address system call yang benar, dia akan mentransfer kontrol ke system call tersebut. Mari kita lihat dimana sys_read() di definisikan, dalam file:
 '''fs/read_write.c'''

@@ Line 69: / Line 69: @@
 '''arch/ppc/kernel/misc.S'''
-The syscall table contains the addresses of the functions that implement each system call. For example, the read() system call function is named sys_read. The read() system call number is 3, so the address of sys_read() is in the 4th entry of the system call table (since we start numbering the system calls with 0). We read the data from the address sys_call_table + (3 * word_size) and we get the address of sys_read().
+Tabel syscall berisi address dari function yang mengimplementasikan setiap system call. Contoh, function system call read() bernama sys_read. Nomor system call read() adalah 3, oleh karenanya address dari sys_read() adalah entry ke 4 di tabel system call (karena nomor pertama system call adalah 0). Kita membaca data dari address sys_call_table + (3 * word_size) dan kita akan memperoleh address dari sys_read().
 After DoSyscall has looked up the correct system call address, it transfers control to that system call. Let's look at where sys_read() is defined, in the file:

@@ Line 65: / Line 65: @@
 '''arch/ppc/kernel/entry.S'''
-Eventually, this function loads up the address of the syscall table and indexes into it using the system call number. The syscall table is what the OS uses to translate from a system call number to a particular system call. The system call table is named sys_call_table and defined in:
+Pada saatnya, function ini akan me-load address dari tabel syscall dan index ke address tersebut menggunakan nomor system call . Tabel syscall adalah apa yang digunakan oleh sistem operasi (OS) untuk menterjemahkan nomor system call ke system call tertentu. Tabel system call bernama sys_call_table didefinisikan di:
 '''arch/ppc/kernel/misc.S'''

← Older revision		Revision as of 03:25, 2 April 2013
Line 14:		Line 14:

	Instruksi di alamat yang baru akan menyimpan state user program, menentukan sistem call apa yang kita inginkan, kemudian call fuction tersebut di kernel yang mengimplementasikan system call, setelah selesai maka mengembalikan program state, dan kembali ke user program. Sebuah system call adalah salah satu cara agar function yang di definisikan dalam device driver untuk bisa di panggil.		Instruksi di alamat yang baru akan menyimpan state user program, menentukan sistem call apa yang kita inginkan, kemudian call fuction tersebut di kernel yang mengimplementasikan system call, setelah selesai maka mengembalikan program state, dan kembali ke user program. Sebuah system call adalah salah satu cara agar function yang di definisikan dalam device driver untuk bisa di panggil.
		+
		+	Bagi yang ingin mendalami lebih lanjut, di persilahkan untuk membaca selanjutnya.

	==Contoh System Call==		==Contoh System Call==

@@ Line 57: / Line 57: @@
           .long   ret
-li stands for "load immediate", which means that a constant value known at compile time is stored in a register. First, trap is loaded into the register r10. On the next line, that value is stored on the address given by TRAP(r11). TRAP(r11) and the next two lines do some hardware specific bit manipulation. After that we call the tfer function (i.e. the transfer_to_handler function), which does yet more housekeeping, and then transfers control to hdlr (i.e. DoSyscall). Note that transfer_to_handler loads the address of the handler from the link register, which is why you see .long DoSyscall instead of bl DoSyscall.
+li singkatan dari "load immediate", yang berarti nilai kontanta yang diketahui saat waktu compile di simpan di register. Pertama kali, trap di load ke register r10. Di kalimat selanjutnya, nilai tersebut di simpan ke address yang diberikan oleh TRAP(r11). TRAP(r11) dan dua kalimat selanjutnya melakukan manipulasi bit spesifik, yang pada dasarnya melakukan housekeeping, dan kemudian men-transfer kontrol ke register, oleh karenanya kita akan melihat .long DoSyscall bukan bl DoSyscall.
-Now, let's look at DoSyscall. It's in the file:
+Selanjutnya, mari kita lihat DoSyscall. Ini ada di file:
 '''arch/ppc/kernel/entry.S'''

@@ Line 15: / Line 15: @@
 Instruksi di alamat yang baru akan menyimpan state user program, menentukan sistem call apa yang kita inginkan, kemudian call fuction tersebut di kernel yang mengimplementasikan system call, setelah selesai maka mengembalikan program state, dan kembali ke user program. Sebuah system call adalah salah satu cara agar function yang di definisikan dalam device driver untuk bisa di panggil.
-==A system call example==
+==Contoh System Call==
-This is a good place to start showing code to go along with the theory. We'll follow the progress of a read() system call, starting from the moment the system call instruction is executed. The PowerPC architecture will be used as an example for the architecture specific part of the code. On the PowerPC, when you execute a system call, the processor jumps to the address 0xc00. The code at that location is defined in the file:
+Berikut kita akan mulai memperlihatkan code beserta sedikit teorinya. Kita akan mengikuti gerakan dari system call read(), mulai dari instruksi system call di jalankan. Arsitektur PowerPC akan digunakan sebagai contoh dari code yang spesifik arsitektur. Di PowerPC, saat kita menjalankan system call, processor akan jump ke address 0xc00. Code pada lokasi ini di definisikan pada file:
-It looks something like this:
+ arch/ppc/kernel/head.S
   /* System call */
@@ Line 32: / Line 33: @@
           EXCEPTION(0xe00, Trap_0e, UnknownException, EXC_XFER_EE)
-What this code does is save some state and call another function called DoSyscall. Here's a more detailed explanation (feel free to skip this part):
+Yang akan dilakukan oleh code ini adalah menyimpan state program, dan call function DoSyscall. Berikut adalah penjelasan lebih detail:
-EXCEPTION_PROLOG is a macro that handles the switch from user to kernel space, which requires things like saving the register state of the user process. EXC_XFER_EE_LITE is called with the address of this routine, and the address of the function DoSyscall. Eventually, some state will be saved and DoSyscall will be called. The next two lines save two exception vectors on the addresses 0xd00 and 0xe00.
+* EXC_XFER_EE_LITE akan dipanggil menggunakan address dari route tersebut, dan address dari function DoSyscall. Pada suatu saat, register akan di simpan dan DoSyscall akan di panggil. Dua kalimat selanjutnya adalah exception vector pada address 0xd00 dan 0xe00.
-EXC_XFER_EE_LITE looks like this:
+EXC_XFER_EE_LITE akan tampak sebagai berikut:
   #define EXC_XFER_EE_LITE(n, hdlr)       \
@@ Line 42: / Line 45: @@
                             ret_from_except)
- EXC_XFER_TEMPLATE is another macro, and the code looks like this:
+EXC_XFER_TEMPLATE adalah macro, dan code akan tampak sebagai berikut:
   #define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret)     \
@@ Line 58: / Line 61: @@
 Now, let's look at DoSyscall. It's in the file:
-arch/ppc/kernel/entry.S
+'''arch/ppc/kernel/entry.S'''
 Eventually, this function loads up the address of the syscall table and indexes into it using the system call number. The syscall table is what the OS uses to translate from a system call number to a particular system call. The system call table is named sys_call_table and defined in:
-arch/ppc/kernel/misc.S
+'''arch/ppc/kernel/misc.S'''
 The syscall table contains the addresses of the functions that implement each system call. For example, the read() system call function is named sys_read. The read() system call number is 3, so the address of sys_read() is in the 4th entry of the system call table (since we start numbering the system calls with 0). We read the data from the address sys_call_table + (3 * word_size) and we get the address of sys_read().
 After DoSyscall has looked up the correct system call address, it transfers control to that system call. Let's look at where sys_read() is defined, in the file:
 fs/read_write.c
 This function finds the file struct associated with the fd number you passed to the read() function. That structure contains a pointer to the function that should be used to read data from that particular kind of file. After doing some checks, it calls that file-specific read function in order to actually read the data from the file, and then returns. This file-specific function is defined somewhere else - the socket code, filesystem code, or device driver code, for example. This is one of the points at which a specific kernel subsystem finally interfaces with the rest of the kernel. After our read function finishes, we return from the sys_read(), back to DoSyscall(), which switches control to ret_from_except, which is in defined in:
-arch/ppc/kernel/entry.S
+'''arch/ppc/kernel/entry.S'''
 This checks for tasks that might need to be done before switching back to user mode. If nothing else needs to be done, we fall through to the restore function, which restores the user process's state and returns control back to the user program. There! Your read() call is done! If you're lucky, you even got your data back.
@@ Line 85: / Line 89: @@
 Have fun!
 ==Referensi==

← Older revision		Revision as of 02:27, 2 April 2013
Line 14:		Line 14:

	Instruksi di alamat yang baru akan menyimpan state user program, menentukan sistem call apa yang kita inginkan, kemudian call fuction tersebut di kernel yang mengimplementasikan system call, setelah selesai maka mengembalikan program state, dan kembali ke user program. Sebuah system call adalah salah satu cara agar function yang di definisikan dalam device driver untuk bisa di panggil.		Instruksi di alamat yang baru akan menyimpan state user program, menentukan sistem call apa yang kita inginkan, kemudian call fuction tersebut di kernel yang mengimplementasikan system call, setelah selesai maka mengembalikan program state, dan kembali ke user program. Sebuah system call adalah salah satu cara agar function yang di definisikan dalam device driver untuk bisa di panggil.
−
−
−	That was the whirlwind tour of how a system call works. Next, we'll go into minute detail for those who are curious about exactly how the kernel does all this. Don't worry if you don't quite understand all of the details - just remember that this is one way that a function in the kernel can end up being called, and that no magic is involved. You can trace the control flow all the way through the kernel - with difficulty sometimes, but you can do it.

	==A system call example==		==A system call example==