Re: [Pmk-users] Can PMK do things like AC_TRY_RUN?

[Damien C. <mip...@us...>]

Erik de Castro Lopo wrote:
> On Tue, 01 Feb 2005 17:03:01 +0100
> Damien Couderc <mip...@us...> wrote:
>>The
>>solution in my mind was to replace scripts by data files. So the threat
>>is located only in pmk code instead of every configure scripts.
>>
>>Until now we always found an alternative for AC_TRY_RUN and i hope we'll
>>always succeed in that :)
> If you are attempting to replace autoconf, then I think you will fail
> if you cannot provide a facility like AC_TRY_RUN. YOu can replace
> certain specific uses of it, but not the general case.

Hopefully we don't expect to replace autoconf. Our goals are different,
this is why PMK is called an alternative.

> In the general case, a developer finds some bug or feature that can only
> be detected at run time and would like to detect the presense/absence
> of that feature at configure time.

Well i disagree with you on that.
Broken code has nothing to do with dependencies. those bugs have to be
fixed upstream. Who would want to run something broken instead of
updating to a fixed release ?
So i expect to stand on my position concerning AC_TRY_RUN until i got a
good argument to not do so. Anyway if even this happens then PMK has no
future as security is a great part of it's goals.

> The only way to do this in the general case is to provide a feature
> like AC_TRY_RUN, possibly using something like a chroot jail.

Using chroot means the necessity to run pmk as root. I find it a bit
overkill :)

>>I've looked quickly at your m4 macro so i get the main idea of what
>>you're checking. Now i'm wondering if this is a bug or a feature, could
>>you provide me an URL that explain a bit more this phenomenon ?
>
> There is no URL. As far as I am aware, I am the only person who uses
> this "feature".
[detail]
> which I consider the "correct" thing to do. X86 CPUs, only do the
> "correct" thing on negative floats which means I still need an if
> statement to check for positive floats that would overflow.
> Other CPUs? I don't know; so I use AC_TRY_RUN.

Well i'm a bit amazed by this problem. Honestly i don't understand how
you can be the only one to have caught this bug.
I suppose that you must have tested this with many compilers and
operating systems that runs powerpc to be sure it was in the core cpu.
So i wonder whether you tried to contact anybody about that issue ?

> So, I've explained what my M4 macro does, but I urge you not to address
> this specific issue but the general issue that AC_TRY_RUN solves.

Well the way i see that is a check done by pmksetup as it is pure
hardware bug. Concerning the general "issue" you already got my answer
above.

Thanks,
Damien