Re: Building RedBoot for SH3 targets with new toolchain

[Bart Veer <bartv@ecoscentric.com>]

>>>>> "John" == John Dallaway <john@dallaway.org.uk> writes:

    John> Hi Andrew
    John> Andrew Lunn wrote:

    >>> Taking all these things into account, plus the desire to avoid
    >>> further delays to the eCos 3.0 release, I think it preferable
    >>> to stick with the stock mpfr and gmp DLLs for the
    >>> Cygwin-hosted toolchains. We must document the need to install
    >>> the relevant Cygwin packages though, and add an entry to the
    >>> FAQ.
    >> 
    >> Would it be possible to detect at build time if these DLLs are
    >> installed? But a custom build rule with the highest priority in
    >> infra, or HAL which will test if this files exist and stop and
    >> print an useful error message if they are not installed?
    >> 
    >> The way cygwin is silently failing is not nice...

    John> The failure mode is certainly not nice. I expect that the
    John> mpfr and gmp DLLs are loaded explicitly by the compiler
    John> using LoadLibrary() and failure is not being reported at the
    John> application level.

    John> We could emit a _warning_ message using a custom rule. An
    John> _error_ message would be too strong since older toolchains
    John> do not use mpfr and gmp. However, it seems cleaner to keep
    John> such testing out of the build process and perform the tests
    John> in the eCos install script instead when the relevant
    John> toolchains are being installed. Having said that, I
    John> appreciate that experienced eCos developers may not use the
    John> install script.

Just how much does it save to link mpfr and gmp dynamically instead of
statically? Ditto for intl and iconv? If it only makes a small
difference I would much prefer to keep things robust and use static
links - and as a useful side effect, avoid problems if updated cygwin
versions of these packages have compatibility issues. Or when moving
toolchains between machines with slightly different cygwin setups. And
no doubt there are plenty of other failure scenarios.

I would not mind so much if the users were given sensible error
messages that explained exactly how to resolve the problem, but silent
failures are going to give a really bad impression to anybody just
starting out with eCos. Especially since the chances are high that any
installation instructions will have received, at best, a cursory
glance.

Bart

-- 
Bart Veer                                   eCos Configuration Architect
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