Re: [ECOS] proposal modification to ecosconfig

[Bart Veer <bartv at redhat dot com>]

>>>>> "Jifl" == Jonathan Larmour <jlarmour@redhat.com> writes:

    Jifl> Bart Veer wrote:
    >> 
    >> Some years back, when eCos builds involved a Tcl script pkgconf.tcl
    >> rather than the current ecosconfig, I did try experimenting with
    >> $(AR) but ran into problems. When removing an entry from the archive
    >> $(AR) would very occasionally get confused and leave behind a broken
    >> archive. Unfortunately I never managed to produce a clean testcase, so
    >> I was unable to investigate further. It is possible that this problem
    >> has gone away by now, but it is also possible that it might still
    >> manifest for some of the targets and cause further confusion.

    Jifl> I don't understand - we currently use $(AR) already.

Yes, but only to add or replace archive members. It was removing
members that caused occasional problems.

    >> Another concern is the two extra invocations of $(AR) for each
    >> package. That adds a fair bit of file I/O to eCos builds, so I would
    >> want to consider the actual time overheads when using either a Linux
    >> or a cygwin host.

    Jifl> That's a valid concern, especially for cygwin. But there
    Jifl> aren't _that_ many packages. And when comparing build
    Jifl> performance vs. accuracy, I opt for accuracy, unless it's
    Jifl> really bad.

It will slow down every build, and it will be fairly rare that the
$(AR) invocations should ever have an effect: only when you have
changed a configuration option that causes a file to be removed from
the build. All other failure modes remain.

    >> As Jifl has already mentioned, there are other problems with the
    >> current makefile generation code and hopefully a rewrite will happen
    >> soon - other work permitting. This particular problem would certainly
    >> be resolved by the rewrite.

    Jifl> But is this patch a reasonable interim solution? If the
    Jifl> rewrite is that close it shouldn't matter ;-).

Unfortunately it involves modifying the makefile generator in
host/tools/configtool/common/common/build.cxx and rebuilding
ecosconfig and configtool binaries, rather than just modifying
pkgconf/rules.mak. That makes it a somewhat bigger change, and not so
easy to revert if things do go wrong.

My personal preference would be to defer this until the rewrite, but
if you want to make the changes then feel free.

Bart