From e7cfb3b46935ccb8b2c3520fc478aeff61f22779 Mon Sep 17 00:00:00 2001
From: Scott Rifenbark <scott.m.rifenbark@intel.com>
Date: Wed, 7 Dec 2011 15:11:32 -0800
Subject: [PATCH] documentation/poky-ref-manual/usingpoky.xml: Removed comments

Removed some comments that were buried in the file that were
notes for working on the sstate section.

(From yocto-docs rev: bd03315031bbb1b682dcd2253f85fc184822a28e)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
 documentation/poky-ref-manual/usingpoky.xml | 99 ---------------------
 1 file changed, 99 deletions(-)

diff --git a/documentation/poky-ref-manual/usingpoky.xml b/documentation/poky-ref-manual/usingpoky.xml
index eb1f9cb045..1e21c93778 100644
--- a/documentation/poky-ref-manual/usingpoky.xml
+++ b/documentation/poky-ref-manual/usingpoky.xml
@@ -298,107 +298,8 @@
             <ulink url='http://git.yoctoproject.org/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54'>commit</ulink>.
         </note>
     </section>
- 
-
-<!--
-
-        <section id="considering-shared-state-cache">
-            <title>Considering Shared State Cache</title>
-
-            <para>
-                What is shared state in general.
-                Benefits?
-                How we handle things 
-                (reference https://lists.yoctoproject.org/pipermail/yocto/2011-March/001157.htm),
-                which is RP's dissertation on how YP solved it.
-                We need to talk a bit about checksum generation for tasks and how the 
-                sstate code uses them to figure out what needs rebuilt and what can be re-loaded
-                from the sstate cache.  
-                Need to tell about cases where an implicit change can mess things up and under
-                normal situations the state in the sstate cache would be used but it shouldn't be.
-                This is the scenario described by bug 1500 - typical case.  
-                Then we talk about how we can invalidate parts of the cache on a per-class basis
-                if needed.  
-
-                there is a discussion at 
-                https://lists.yoctoproject.org/pipermail/yocto/2011-March/001157.htm
-                that talks about sstate and how the YP team attacked and solved the problem. 
-                This is probably a good place to get information from to broach the whole
-                sstate concept. 
-
-                YP, by default, builds from scratch.
-                This is good but it means spending a lot of time rebuilding things that don't 
-                necessarily need rebuilding.
-
-                The SSTATE_DIR variable points to the directory for the shared state cache that 
-                is used during a build.
-
-                A task's inputs have a checksum or signature associated with them.
-                If the checksum changes on an input as compared to a prior build, the task must be rerun.
-                The shared state (sstate) code keeps track of what output is generated by which tasks.
-                So if a task's inputs have not changed then the output associated with the task can 
-                be yanked from some place and re-used.  No re-build required for that particular task.
-
-                A "run" shell script is created for each task.
-                You can create a checksum for the task based on the inputs to the task.
-                When you have this checksum, the code will look at it and compare it to the previous
-                checksum to see if the task's inputs have changed.
-                If so, the task needs to be re-run.
-
-                Python tasks have python functions that access variables. 
-                Python functions will call other python functions as well.
-                The solution was to figure out the variable and function dependencies and create
-                a checksum value for the data coming into the python task.
-
-                Here is a conversation with Mark Hatle regarding bug 1500 (638 is related):
-
-(01:23:34 PM) scottrif: mark - you have a minute?
-(01:34:05 PM) Mark Hatle: sure..
-(01:34:11 PM) Mark Hatle: might be a bit slow to respond, but I'm here
-(01:34:45 PM) scottrif: Hi - I am looking at bug 1500 and trying to get a bit of better understanding.  Here is the link to the bug - http://bugzilla.pokylinux.org/show_bug.cgi?id=1500
-(01:35:25 PM) scottrif: It seems that the key for the user here is to when to "Know" when to put some comments into a function to invalidate certain areas of sstate.
-(01:35:49 PM) Mark Hatle: what the issue is, if you make changes to something that is not normally calculated in the checksums for sstate, then you can get package mismatches..
-(01:35:50 PM) scottrif: This trick of "knowing"... does it need to be explained?
-(01:36:25 PM) Mark Hatle: The developer will have to know they made such a change..  Then to deal with this, they can use a patch like what is referenced to cause specific steps to be invalidated and various steps re-run..
-(01:37:01 PM) scottrif: so my question is will the developer know when they make a change like this?
-(01:37:04 PM) Mark Hatle: In this case, we change part of the back-end packaging mechanisms.. which changed internal dependency generation.  The sstate code does not checksum the internal dependency generation, it assumes that is code that doesn't change behavior
-(01:37:24 PM) Mark Hatle: They should understand the ramifications of their changes — and thus know they need to do this.
-(01:37:46 PM) Mark Hatle: Examples of times you need to do this.  Back end packaging changes occur — i.e. you change the format of dependency generation..
-(01:38:38 PM) scottrif: do you have any other examples?
-(01:38:39 PM) Mark Hatle: when you change a recipe itself, source code.. it is -not- necessary to do this
-(01:38:49 PM) Mark Hatle: RP might be better at examples of when to do it..
-(01:39:11 PM) scottrif: right - If I change a recipe then every thing dependent further down the line gets regenerated right?
-(01:39:17 PM) Mark Hatle: This should never be necessary when a recipe changes.. it will only be necessary when some classes or back-end (packaging frameworks) change..
-(01:39:21 PM) Mark Hatle: ya
-(01:39:33 PM) Mark Hatle: Another way to think of this is implicit dependencies..
-(01:40:01 PM) Mark Hatle: I change RPM..  If you build something that produces an RPM package.. the assumption is the RPM package won't change, even if the RPM binary changes..
-(01:40:10 PM) Mark Hatle: If the format of the package changes.. you would need to do this
-(01:40:53 PM) Mark Hatle: RP can probably give you an idea of the various implicit dependencies, and which ones this type of change is needed for
-(01:41:26 PM) scottrif: okay.  I am struggling a bit with how to word it.  what I will do is write something up and send it out to you and RP for a look
-(01:41:47 PM) Mark Hatle: ya, I understand.. it's an odd set of situations that can cause this — but we definitely need to document it
-(01:42:01 PM) scottrif: I just want the information to help the user understand the conditions when they will want to invalidate parts of the sstate
-(01:42:18 PM) scottrif: I will likely use the RPM example as the case to illustrate it
-(01:42:26 PM) scottrif: as it seems pretty straight forward
-(01:42:28 PM) Mark Hatle: yup.  Key thing is it's only needed on implicit dependencies..  Normal case is back end packaging format changes..
-(01:42:31 PM) Mark Hatle: yup
-(01:42:47 PM) scottrif: ok - thanks Mark
-
-          Here is what RP wants to address 1500:
-
-If its desired to change the checksum of a given subset of tasks, maybe
-due to a change which isn't directly visible in the code itself (e.g. a
-tool changed its output) its possible to do this by changing a function
-comments since the sstate checksums include the body of functions. To
-invalidate package sstate files for example, do_package or one of the
-functions it calls can be changed, even if its just a cosmetic change to
-the commends.
-http://git.yoctoproject.org/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54
-is an example of a commit which does this.
-
--->
 </section>
 
-
 <section id='usingpoky-install'>
     <title>Installing and Using the Result</title>