[PATCH] Headers for the x86 subtree

Attilio Rao attilio at freebsd.org
Wed Oct 27 21:55:25 UTC 2010


2010/10/27 John Baldwin <jhb at freebsd.org>:
> On Wednesday, October 27, 2010 5:25:20 pm Attilio Rao wrote:
>> 2010/10/27 John Baldwin <jhb at freebsd.org>:
>> > On Wednesday, October 27, 2010 4:00:15 pm Attilio Rao wrote:
>> >> 2010/10/27 John Baldwin <jhb at freebsd.org>:
>> >> > On Wednesday, October 27, 2010 10:56:06 am Attilio Rao wrote:
>> >> >> This patch should convert a (simple and 100% shared between amd64 and
>> >> >> i386 header) under the x86 sub-tree. Please note that in this patch I
>> >> >> "svn cp" the file from sys/amd64/include/mptable.h into
>> >> >> sys/x86/include/mptable.h:
>> >> >> http://www.freebsd.org/~attilio/headers-x86.diff
>> >> >>
>> >> >> This is someway a POC, that I really want to get in. The idea is
>> >> >> simple and someway follows the pc98 case (even if not entirely): the
>> >> >> files under machine/include/* became just mere stubs for x86/include/*
>> >> >> contents and redirect there.
>> >> >> This won't particulary help reducing the number of available files,
>> >> >> but generally removing verbatim and would also be the way to go for
>> >> >> handling MFCs.
>> >> >> If you find this is the right way I'll commit the fix and start moving
>> >> >> other files as time permits.
>> >> >
>> >> > No, we want to do this differently because we also want this to work in
>> >> > userland.  (e.g. I'd like to outright move mca.h to x86/include and then use
>> >> > '#include <x86/mca.h>' in both kernel and userland for it).  We'd need some
>> >> > special glue to setup an 'x86' symlink during a kernel build that points to
>> >> > @/x86/include as we do now to setup an 'i386' link for pc98 kernels.
>> >> >
>> >> > We'd also need to install the x86 headers into /usr/include during an
>> >> > installworld.  Warner has some more pointers on this I think.
>> >>
>> >> So you probabilly are suggesting to go w/ the "pc98 approach".
>> >> I'm fine with it, I'll try to look for how it works and implement as well.
>> >
>> > Thanks.  I think it is fine to use '#include <x86/foo.h>' in code directly
>> > with this approach as well.  I only think we should provide wrappers in
>> > /usr/include/machine if compatibility is needed.  mca.h and mptable.h
>> > shouldn't need compatibility for example, but specialreg.h might.
>>
>> I'd expect to potentially mirror any header, otherwise on which
>> criterias we can say some are needed and other not?
>
> If it is widely used in userland. :)  mptable.h is probably only used by the
> mptable utility which is easily fixed.  It will not be of interest to any 3rd
> party software.  mca.h may eventually be used by third party software, but it
> is very new, so we can probably move it now without causing any harm.
>
> Kernel-only headers such as intr_machdep.h certainly do not need any compat
> wrappers.
>
> We can always add a compat header in machine if we find it is needed, but I'd
> like to minimize the amount of compat cruft as much as possible.

I'd say in general I agree, so let's add them just on-demand is possibly fine.

Thanks,
Attilio


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