Re: [PATCH] Revert "x86: optimize page faults like all otherachitectures and kill notifier cruft"

[Jan Beulich]

>That change has been in the mainline tree for nearly three months.  All
>these affected parties have left it until the eve of 2.6.24 to actually
>tell us about it.  This is causing me sympathy problems :(

Not true - I complained about this on Dec 3rd (attached), with the result of
not getting a response from anyone but Andi (agreeing to restore these
notifiers).

Jan
> --- Begin Message ---
> Ever since I started to try to get at least some fundamental infrastructure
> pieces merged for using NLKD on Linux I was told that direct calls out of
> exception handlers for the sake of an individual (and perhaps even small)
> sub-system is undesirable.
>
> Making the exception notifiers report the right (correct) information (and,
> specific to x86, ensuring they get called in the right place) was one of the
> fundamental things, and just now I see that this is being reverted for (in
> my eyes) no good reason: Instead of adding direct calls to x86, all the
> other architectures should have followed the notifier model in order for
> the infrastructure to be usable by external components, especially if
> these aren't allowed into the kernel.
>
> Am I to conclude that replacing direct calls elsewhere in the tree (in order
> to e.g. avoid all kinds of small sub-components leaving their footprint in
> core files like kernel/fork.c) is no longer a desirable goal, thereby making
> it almost impossible to ever host a kernel debugger *without* having to
> patch core files.
>
> Thanks, Jan
>
>
> --- End Message ---