---

yaml
---
r: 30639
b: refs/heads/master
c: ba262e4
h: refs/heads/master
i:
  30637: 39b9666
  30635: f456674
  30631: ddd63e0
  30623: 0fd28e9
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b07076e6173a2593e369c3375f07c1cd7d78c36f
+refs/heads/master: ba262e4a4d4c23b5e6c15dbb3a99696b562e8035

trunk/CREDITS

@@ -24,6 +24,11 @@ S: C. Negri 6, bl. D3
 S: Iasi 6600
 S: Romania
 
+N: Mark Adler
+E: madler@alumni.caltech.edu
+W: http://alumnus.caltech.edu/~madler/
+D: zlib decompression
+
 N: Monalisa Agrawal
 E: magrawal@nortelnetworks.com
 D: Basic Interphase 5575 driver with UBR and ABR support.

trunk/Documentation/DocBook/kernel-locking.tmpl

@@ -1590,7 +1590,7 @@ the amount of locking which needs to be done.
     <para>
       Our final dilemma is this: when can we actually destroy the
       removed element?  Remember, a reader might be stepping through
-      this element in the list right now: it we free this element and
+      this element in the list right now: if we free this element and
       the <symbol>next</symbol> pointer changes, the reader will jump
       off into garbage and crash.  We need to wait until we know that
       all the readers who were traversing the list when we deleted the

trunk/Documentation/atomic_ops.txt

@@ -157,13 +157,13 @@ For example, smp_mb__before_atomic_dec() can be used like so:
 	smp_mb__before_atomic_dec();
 	atomic_dec(&obj->ref_count);
 
-It makes sure that all memory operations preceeding the atomic_dec()
+It makes sure that all memory operations preceding the atomic_dec()
 call are strongly ordered with respect to the atomic counter
-operation.  In the above example, it guarentees that the assignment of
+operation.  In the above example, it guarantees that the assignment of
 "1" to obj->dead will be globally visible to other cpus before the
 atomic counter decrement.
 
-Without the explicitl smp_mb__before_atomic_dec() call, the
+Without the explicit smp_mb__before_atomic_dec() call, the
 implementation could legally allow the atomic counter update visible
 to other cpus before the "obj->dead = 1;" assignment.
 
@@ -173,11 +173,11 @@ ordering with respect to memory operations after an atomic_dec() call
 (smp_mb__{before,after}_atomic_inc()).
 
 A missing memory barrier in the cases where they are required by the
-atomic_t implementation above can have disasterous results.  Here is
-an example, which follows a pattern occuring frequently in the Linux
+atomic_t implementation above can have disastrous results.  Here is
+an example, which follows a pattern occurring frequently in the Linux
 kernel.  It is the use of atomic counters to implement reference
 counting, and it works such that once the counter falls to zero it can
-be guarenteed that no other entity can be accessing the object:
+be guaranteed that no other entity can be accessing the object:
 
 static void obj_list_add(struct obj *obj)
 {
@@ -291,19 +291,19 @@ to the size of an "unsigned long" C data type, and are least of that
 size.  The endianness of the bits within each "unsigned long" are the
 native endianness of the cpu.
 
-	void set_bit(unsigned long nr, volatils unsigned long *addr);
-	void clear_bit(unsigned long nr, volatils unsigned long *addr);
-	void change_bit(unsigned long nr, volatils unsigned long *addr);
+	void set_bit(unsigned long nr, volatile unsigned long *addr);
+	void clear_bit(unsigned long nr, volatile unsigned long *addr);
+	void change_bit(unsigned long nr, volatile unsigned long *addr);
 
 These routines set, clear, and change, respectively, the bit number
 indicated by "nr" on the bit mask pointed to by "ADDR".
 
 They must execute atomically, yet there are no implicit memory barrier
 semantics required of these interfaces.
 
-	int test_and_set_bit(unsigned long nr, volatils unsigned long *addr);
-	int test_and_clear_bit(unsigned long nr, volatils unsigned long *addr);
-	int test_and_change_bit(unsigned long nr, volatils unsigned long *addr);
+	int test_and_set_bit(unsigned long nr, volatile unsigned long *addr);
+	int test_and_clear_bit(unsigned long nr, volatile unsigned long *addr);
+	int test_and_change_bit(unsigned long nr, volatile unsigned long *addr);
 
 Like the above, except that these routines return a boolean which
 indicates whether the changed bit was set _BEFORE_ the atomic bit
@@ -335,7 +335,7 @@ subsequent memory operation is made visible.  For example:
 		/* ... */;
 	obj->killed = 1;
 
-The implementation of test_and_set_bit() must guarentee that
+The implementation of test_and_set_bit() must guarantee that
 "obj->dead = 1;" is visible to cpus before the atomic memory operation
 done by test_and_set_bit() becomes visible.  Likewise, the atomic
 memory operation done by test_and_set_bit() must become visible before
@@ -474,7 +474,7 @@ Now, as far as memory barriers go, as long as spin_lock()
 strictly orders all subsequent memory operations (including
 the cas()) with respect to itself, things will be fine.
 
-Said another way, _atomic_dec_and_lock() must guarentee that
+Said another way, _atomic_dec_and_lock() must guarantee that
 a counter dropping to zero is never made visible before the
 spinlock being acquired.
 

trunk/Documentation/console/console.txt

@@ -0,0 +1,144 @@
+Console Drivers
+===============
+
+The linux kernel has 2 general types of console drivers.  The first type is
+assigned by the kernel to all the virtual consoles during the boot process.
+This type will be called 'system driver', and only one system driver is allowed
+to exist. The system driver is persistent and it can never be unloaded, though
+it may become inactive.
+
+The second type has to be explicitly loaded and unloaded. This will be called
+'modular driver' by this document. Multiple modular drivers can coexist at
+any time with each driver sharing the console with other drivers including
+the system driver. However, modular drivers cannot take over the console
+that is currently occupied by another modular driver. (Exception: Drivers that
+call take_over_console() will succeed in the takeover regardless of the type
+of driver occupying the consoles.) They can only take over the console that is
+occupied by the system driver. In the same token, if the modular driver is
+released by the console, the system driver will take over.
+
+Modular drivers, from the programmer's point of view, has to call:
+
+	 take_over_console() - load and bind driver to console layer
+	 give_up_console() - unbind and unload driver
+
+In newer kernels, the following are also available:
+
+	 register_con_driver()
+	 unregister_con_driver()
+
+If sysfs is enabled, the contents of /sys/class/vtconsole can be
+examined. This shows the console backends currently registered by the
+system which are named vtcon<n> where <n> is an integer fro 0 to 15. Thus:
+
+       ls /sys/class/vtconsole
+       .  ..  vtcon0  vtcon1
+
+Each directory in /sys/class/vtconsole has 3 files:
+
+     ls /sys/class/vtconsole/vtcon0
+     .  ..  bind  name  uevent
+
+What do these files signify?
+
+     1. bind - this is a read/write file. It shows the status of the driver if
+        read, or acts to bind or unbind the driver to the virtual consoles
+        when written to. The possible values are:
+
+	0 - means the driver is not bound and if echo'ed, commands the driver
+	    to unbind
+
+        1 - means the driver is bound and if echo'ed, commands the driver to
+	    bind
+
+     2. name - read-only file. Shows the name of the driver in this format:
+
+	cat /sys/class/vtconsole/vtcon0/name
+	(S) VGA+
+
+	    '(S)' stands for a (S)ystem driver, ie, it cannot be directly
+	    commanded to bind or unbind
+
+	    'VGA+' is the name of the driver
+
+	cat /sys/class/vtconsole/vtcon1/name
+	(M) frame buffer device
+
+	    In this case, '(M)' stands for a (M)odular driver, one that can be
+	    directly commanded to bind or unbind.
+
+     3. uevent - ignore this file
+
+When unbinding, the modular driver is detached first, and then the system
+driver takes over the consoles vacated by the driver. Binding, on the other
+hand, will bind the driver to the consoles that are currently occupied by a
+system driver.
+
+NOTE1: Binding and binding must be selected in Kconfig. It's under:
+
+Device Drivers -> Character devices -> Support for binding and unbinding
+console drivers
+
+NOTE2: If any of the virtual consoles are in KD_GRAPHICS mode, then binding or
+unbinding will not succeed. An example of an application that sets the console
+to KD_GRAPHICS is X.
+
+How useful is this feature? This is very useful for console driver
+developers. By unbinding the driver from the console layer, one can unload the
+driver, make changes, recompile, reload and rebind the driver without any need
+for rebooting the kernel. For regular users who may want to switch from
+framebuffer console to VGA console and vice versa, this feature also makes
+this possible. (NOTE NOTE NOTE: Please read fbcon.txt under Documentation/fb
+for more details).
+
+Notes for developers:
+=====================
+
+take_over_console() is now broken up into:
+
+     register_con_driver()
+     bind_con_driver() - private function
+
+give_up_console() is a wrapper to unregister_con_driver(), and a driver must
+be fully unbound for this call to succeed. con_is_bound() will check if the
+driver is bound or not.
+
+Guidelines for console driver writers:
+=====================================
+
+In order for binding to and unbinding from the console to properly work,
+console drivers must follow these guidelines:
+
+1. All drivers, except system drivers, must call either register_con_driver()
+   or take_over_console(). register_con_driver() will just add the driver to
+   the console's internal list. It won't take over the
+   console. take_over_console(), as it name implies, will also take over (or
+   bind to) the console.
+
+2. All resources allocated during con->con_init() must be released in
+   con->con_deinit().
+
+3. All resources allocated in con->con_startup() must be released when the
+   driver, which was previously bound, becomes unbound.  The console layer
+   does not have a complementary call to con->con_startup() so it's up to the
+   driver to check when it's legal to release these resources. Calling
+   con_is_bound() in con->con_deinit() will help.  If the call returned
+   false(), then it's safe to release the resources.  This balance has to be
+   ensured because con->con_startup() can be called again when a request to
+   rebind the driver to the console arrives.
+
+4. Upon exit of the driver, ensure that the driver is totally unbound. If the
+   condition is satisfied, then the driver must call unregister_con_driver()
+   or give_up_console().
+
+5. unregister_con_driver() can also be called on conditions which make it
+   impossible for the driver to service console requests.  This can happen
+   with the framebuffer console that suddenly lost all of its drivers.
+
+The current crop of console drivers should still work correctly, but binding
+and unbinding them may cause problems. With minimal fixes, these drivers can
+be made to work correctly.
+
+==========================
+Antonino Daplas <adaplas@pol.net>
+

trunk/Documentation/driver-model/overview.txt

@@ -18,7 +18,7 @@ Traditional driver models implemented some sort of tree-like structure
 (sometimes just a list) for the devices they control. There wasn't any
 uniformity across the different bus types.
 
-The current driver model provides a comon, uniform data model for describing
+The current driver model provides a common, uniform data model for describing
 a bus and the devices that can appear under the bus. The unified bus
 model includes a set of common attributes which all busses carry, and a set
 of common callbacks, such as device discovery during bus probing, bus