On Thursday 20 September 2007 4:26:13 pm Indan Zupancic wrote:
quoted text
> On Thu, September 20, 2007 22:38, Rob Landley wrote:
> > I've been playing with an idea for a while to improve the printk()
> > situation, but it's a more intrusive change than I've had time to bang
> > on.
> >
> > Right now, the first argument to printk() is a loglevel, but it's handled
> > via string concatenation.  I'd like to change that to be an integer, and
> > make it an actual comma-separated first argument.  (Mandatory, not
> > optional.)
> >
> > So instead of:
> >   printk(KERN_NOTICE "Fruit=%d\n", banana);
> > It would now be:
> >   printk(KERN_NOTICE, "Fruit=%d\n", banana);
> >
> > Change the header from:
> >   #define KERN_NOTICE "<5>"
> > to:
> >   #define KERN_NOTICE 5
>
> You have to jump through less hoops if you do:
>
> #define KERN_NOTICE 5,

Less change to the source, but the result is less obvious about what it's 
doing.  I'd personally rather have the churn than wind up with magic 
syntax...

quoted text
> But the problem remains that there are printk's which don't have
> a KERN_* as the first argument. Those are also impossible to get
> rid off in this way, as the loglevel is unknown (and you don't want
> partially printed messages).
>
> So adding the comma is really needed and in addition all printk's
> without a loglevel should get one. Which clutters the code and may
> increase codesize.

It's ok to _explicitly_ not have a loglevel, and thus take a known default.  
The problem is printing out less than a full line, continuing it later, and 
not making obvious at compile time what the level of this chunk is.

quoted text
> A quick scroll through a vmlinux binary shows that there are quite a
> lot areas consisting only of some repeated pattern. Mostly 0x00, but
> also 0x90 and ".GCC: (GNU) 4.2.1.". Getting rid of those would save
> something between 50 and 100KB.

Worse, if you feed an absolute path to O= when you build the kernel out of 
tree, then it uses absolute paths for all the __FILE__ strings and that makes 
kernel BIIIIIG.  (Did that by accident a while back.)  Too bad there's no way 
to keep the __FILE__ strings compressed at runtime and gunzip them as needed 
like busybox does with help messages... :)

Rob
-- 
"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.
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