Re: [PATCH] add a counter in grub_dprintf

[Isaac Dupree]

Javier Martín wrote:
> El sáb, 21-06-2008 a las 16:19 +0200, Robert Millan escribió:
> > But space in post-mbr area is precious, and if we can save a bit, it means
> > less users who will run into trouble in first place.
>
> Disclaimer: the following is just the product of brainstorming from a
> mind tortured by hours of studying projective geometry. Use with care ^^
>
> Why not modify the build system to create _two_ instances of kernel.img,
> one with and another without debugging? grub_mkimage would create the
> normal, smaller core.img (without dprintf) for installing and embedding;
> and store a core_dbg.img in the /boot/grub folder, so that if
> instrumentation is required the only thing the users needs to do is
> chain that debug version of GRUB:
>
>     grub> multiboot /boot/grub/core_dbg.img
>     grub> boot

or even to install it if necessary (if it fits! But multiboot, if it 
works, could help *some* of the time too).  I think that prebuilt debug 
image is important, otherwise when users rebuild a debug version it's 
much more likely to be built differently somehow from the corresponding 
non-debug version (especially if it originally came through a packaging 
system such as Debian).


Robert Millan wrote:
> OTOH, it could add maintainance burden for us when we have to explain
> everyone that they have to rebuild and reinstall GRUB to get the debug
> output _and_ it opens the door for heisenbugs.
>
> But space in post-mbr area is precious, and if we can save a bit, it means
> less users who will run into trouble in first place.

the possibility for heisenbugs does seem very real given the diversity 
of hardware out there.  Would it mitigate this to only disable the 
dprintfs (by default) in space-critical images such as x86 pc?  (or 
would it make things worse...)

-Isaac