Re: [PATCH] framework for building modules externally

[Vesa Jääskeläinen]

Robert Millan wrote:
> On Tue, Nov 04, 2008 at 08:55:52PM +0200, Vesa Jääskeläinen wrote:
>> Robert Millan wrote:
>>> On Sat, Nov 01, 2008 at 01:32:29PM +0100, Robert Millan wrote:
>>>> Hi,
>>>>
>>>> Attached patch makes it possible to build modules externally, by:
>>>>
>>>>   - Installing headers in system include dir.
>>>>
>>>>   - Exporting two ABI tags (a build-time macro and a run-time variable)
>>>>     for run-time comparison.
>>>>
>>>>   - Exporting a makefile with COMMON_*FLAGS variables.
>>> Looks like I missed some important details.  The headers and some macros are
>>> not enough, as we need to reproduce part of the build system to build a 
>>> module
>>> externally.  This new patch provides the following:
>> Interesting idea. However how do you define GRUB ABI :) ? What is it,
>> kernel, certain set of modules, or how :) ?
> 
> Anything that can possibly break an external module.  I.e. any interface
> exported by either the kernel or any of the modules.
> 
> (I expect we'd bump this number a lot)

Did you have some plan how to automate this ABI versioning :) ? If it is
not automated I can almost guarantee that we get it wrong at one point
of time :)

>> Versioning of the modules would be a good idea indeed to make sure
>> mismatched modules are not tried together.
> 
> This should never happen if user always runs grub-install (which he should
> do anyway unless he's looking for trouble).  My idea for external modules is
> that a separate package can put them in $pkglibdir and then grub-install will
> automaticaly include them the next time it's called.

How do you treat differences in ABI ?

Dis-allow loading of module with different value of ABI ? Or were you
planning that module itself adapts to different versions of GRUB 2 ABI's?