[Devel] Re: [PATCH 3/7] make CONFIG_CHECKPOINT depend on CONFIG_CHECKPOINT_SUPPORT

[Nathan Lynch]

Dave Hansen <dave at linux.vnet.ibm.com> wrote:

> On Wed, 2009-03-25 at 18:02 -0500, Nathan Lynch wrote:
> > 
> > diff --git a/checkpoint/Kconfig b/checkpoint/Kconfig
> > index e91e0fd..760c450 100644
> > --- a/checkpoint/Kconfig
> > +++ b/checkpoint/Kconfig
> > @@ -1,6 +1,6 @@
> >  config CHECKPOINT
> >         bool "Enable checkpoint/restart (EXPERIMENTAL)"
> > -       depends on (X86_32 || (S390 && 64BIT)) && EXPERIMENTAL
> > +       depends on CHECKPOINT_SUPPORT && EXPERIMENTAL
> >         help
> >           Application checkpoint/restart is the ability to save the
> >           state of a running application so that it can later resume
> 
> Yeah, this is the right way to do it, very nice.

Thanks Dave.

 
> Could we add a wee little ARCH_ prepend on 'CHECKPOINT_SUPPORT' in
> there?  That way, people at least know where to go looking when they
> want to find out why it isn't enabled.  

You have a point, but I'd prefer to keep the name unchanged:

* There doesn't seem to be a strong convention for putting the 'ARCH'
  string in such symbols.  Examples: LOCKDEP_SUPPORT, HAVE_KPROBES,
  STACKTRACE_SUPPORT.  Plenty of counter-examples, too, but there's no
  standard practice AFAICT.

* Making the string more verbose means people are more likely to get
  it wrong e.g. CONFIG_CHECKPOINT_ARCH_SUPPORT (and this sort of thing
  can go unnoticed for a while).

* Implementers can grep or cscope for it and figure it out pretty
  quickly, and they likely would do that anyway regardless of what it's
  called.

Prepending ARCH_ would imply the right things, but with a comment, we
can be explicit.


commit 07087d9295d1c4dcd7e79b19d70abf19370f59da
Author: Nathan Lynch <ntl at pobox.com>
Date:   Wed Mar 25 21:32:30 2009 -0500

    document CHECKPOINT_SUPPORT
    
    Make CHECKPOINT_SUPPORT's intended use clear with a comment in
    checkpoint/Kconfig.
    
    Signed-off-by: Nathan Lynch <ntl at pobox.com>

diff --git a/checkpoint/Kconfig b/checkpoint/Kconfig
index 760c450..1761b0a 100644
--- a/checkpoint/Kconfig
+++ b/checkpoint/Kconfig
@@ -1,3 +1,7 @@
+# Architectures should define CHECKPOINT_SUPPORT when they have
+# implemented the hooks for processor state etc. needed by the
+# core checkpoint/restart code.
+
 config CHECKPOINT
 	bool "Enable checkpoint/restart (EXPERIMENTAL)"
 	depends on CHECKPOINT_SUPPORT && EXPERIMENTAL
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