---

yaml
---
r: 20445
b: refs/heads/master
c: 69aa234
h: refs/heads/master
i:
  20443: c4ec055
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b05de01ae1c76b7d61da21bbcc26345bf7a9052f
+refs/heads/master: 69aa234b918c0d9bc4a20cd6d4453aaa3418f457

trunk/Documentation/kprobes.txt

@@ -136,20 +136,17 @@ Kprobes, jprobes, and return probes are implemented on the following
 architectures:
 
 - i386
-- x86_64 (AMD-64, EM64T)
+- x86_64 (AMD-64, E64MT)
 - ppc64
-- ia64 (Does not support probes on instruction slot1.)
+- ia64 (Support for probes on certain instruction types is still in progress.)
 - sparc64 (Return probes not yet implemented.)
 
 3. Configuring Kprobes
 
 When configuring the kernel using make menuconfig/xconfig/oldconfig,
-ensure that CONFIG_KPROBES is set to "y".  Under "Instrumentation
-Support", look for "Kprobes".
-
-So that you can load and unload Kprobes-based instrumentation modules,
-make sure "Loadable module support" (CONFIG_MODULES) and "Module
-unloading" (CONFIG_MODULE_UNLOAD) are set to "y".
+ensure that CONFIG_KPROBES is set to "y".  Under "Kernel hacking",
+look for "Kprobes".  You may have to enable "Kernel debugging"
+(CONFIG_DEBUG_KERNEL) before you can enable Kprobes.
 
 You may also want to ensure that CONFIG_KALLSYMS and perhaps even
 CONFIG_KALLSYMS_ALL are set to "y", since kallsyms_lookup_name()
@@ -265,18 +262,18 @@ at any time after the probe has been registered.
 
 5. Kprobes Features and Limitations
 
-Kprobes allows multiple probes at the same address.  Currently,
-however, there cannot be multiple jprobes on the same function at
-the same time.
+As of Linux v2.6.12, Kprobes allows multiple probes at the same
+address.  Currently, however, there cannot be multiple jprobes on
+the same function at the same time.
 
 In general, you can install a probe anywhere in the kernel.
 In particular, you can probe interrupt handlers.  Known exceptions
 are discussed in this section.
 
-The register_*probe functions will return -EINVAL if you attempt
-to install a probe in the code that implements Kprobes (mostly
-kernel/kprobes.c and arch/*/kernel/kprobes.c, but also functions such
-as do_page_fault and notifier_call_chain).
+For obvious reasons, it's a bad idea to install a probe in
+the code that implements Kprobes (mostly kernel/kprobes.c and
+arch/*/kernel/kprobes.c).  A patch in the v2.6.13 timeframe instructs
+Kprobes to reject such requests.
 
 If you install a probe in an inline-able function, Kprobes makes
 no attempt to chase down all inline instances of the function and
@@ -293,14 +290,18 @@ from the accidental ones.  Don't drink and probe.
 
 Kprobes makes no attempt to prevent probe handlers from stepping on
 each other -- e.g., probing printk() and then calling printk() from a
-probe handler.  If a probe handler hits a probe, that second probe's
-handlers won't be run in that instance, and the kprobe.nmissed member
-of the second probe will be incremented.
-
-As of Linux v2.6.15-rc1, multiple handlers (or multiple instances of
-the same handler) may run concurrently on different CPUs.
-
-Kprobes does not use mutexes or allocate memory except during
+probe handler.  As of Linux v2.6.12, if a probe handler hits a probe,
+that second probe's handlers won't be run in that instance.
+
+In Linux v2.6.12 and previous versions, Kprobes' data structures are
+protected by a single lock that is held during probe registration and
+unregistration and while handlers are run.  Thus, no two handlers
+can run simultaneously.  To improve scalability on SMP systems,
+this restriction will probably be removed soon, in which case
+multiple handlers (or multiple instances of the same handler) may
+run concurrently on different CPUs.  Code your handlers accordingly.
+
+Kprobes does not use semaphores or allocate memory except during
 registration and unregistration.
 
 Probe handlers are run with preemption disabled.  Depending on the
@@ -315,18 +316,11 @@ address instead of the real return address for kretprobed functions.
 (As far as we can tell, __builtin_return_address() is used only
 for instrumentation and error reporting.)
 
-If the number of times a function is called does not match the number
-of times it returns, registering a return probe on that function may
-produce undesirable results.  We have the do_exit() case covered.
-do_execve() and do_fork() are not an issue.  We're unaware of other
-specific cases where this could be a problem.
-
-If, upon entry to or exit from a function, the CPU is running on
-a stack other than that of the current task, registering a return
-probe on that function may produce undesirable results.  For this
-reason, Kprobes doesn't support return probes (or kprobes or jprobes)
-on the x86_64 version of __switch_to(); the registration functions
-return -EINVAL.
+If the number of times a function is called does not match the
+number of times it returns, registering a return probe on that
+function may produce undesirable results.  We have the do_exit()
+and do_execve() cases covered.  do_fork() is not an issue.  We're
+unaware of other specific cases where this could be a problem.
 
 6. Probe Overhead
 
@@ -353,12 +347,14 @@ k = 0.77 usec; j = 1.31; r = 1.26; kr = 1.45; jr = 1.99
 
 7. TODO
 
-a. SystemTap (http://sourceware.org/systemtap): Provides a simplified
-programming interface for probe-based instrumentation.  Try it out.
-b. Kernel return probes for sparc64.
-c. Support for other architectures.
-d. User-space probes.
-e. Watchpoint probes (which fire on data references).
+a. SystemTap (http://sourceware.org/systemtap): Work in progress
+to provide a simplified programming interface for probe-based
+instrumentation.
+b. Improved SMP scalability: Currently, work is in progress to handle
+multiple kprobes in parallel.
+c. Kernel return probes for sparc64.
+d. Support for other architectures.
+e. User-space probes.
 
 8. Kprobes Example
 
@@ -415,7 +411,8 @@ int init_module(void)
 		printk("Couldn't find %s to plant kprobe\n", "do_fork");
 		return -1;
 	}
-	if ((ret = register_kprobe(&kp) < 0)) {
+	ret = register_kprobe(&kp);
+	if (ret < 0) {
 		printk("register_kprobe failed, returned %d\n", ret);
 		return -1;
 	}

trunk/Documentation/mips/AU1xxx_IDE.README

@@ -95,13 +95,11 @@ CONFIG_BLK_DEV_IDEDMA_PCI=y
 CONFIG_IDEDMA_PCI_AUTO=y
 CONFIG_BLK_DEV_IDE_AU1XXX=y
 CONFIG_BLK_DEV_IDE_AU1XXX_MDMA2_DBDMA=y
+CONFIG_BLK_DEV_IDE_AU1XXX_BURSTABLE_ON=y
 CONFIG_BLK_DEV_IDE_AU1XXX_SEQTS_PER_RQ=128
 CONFIG_BLK_DEV_IDEDMA=y
 CONFIG_IDEDMA_AUTO=y
 
-Also define 'IDE_AU1XXX_BURSTMODE' in 'drivers/ide/mips/au1xxx-ide.c' to enable
-the burst support on DBDMA controller.
-
 If the used system need the USB support enable the following kernel configs for
 high IDE to USB throughput.
 
@@ -117,8 +115,6 @@ CONFIG_BLK_DEV_IDE_AU1XXX_SEQTS_PER_RQ=128
 CONFIG_BLK_DEV_IDEDMA=y
 CONFIG_IDEDMA_AUTO=y
 
-Also undefine 'IDE_AU1XXX_BURSTMODE' in 'drivers/ide/mips/au1xxx-ide.c' to
-disable the burst support on DBDMA controller.
 
 ADD NEW HARD DISC TO WHITE OR BLACK LIST
 ----------------------------------------