Re: [Qemu-devel] [PATCH 0/3] configure: symlink directories, not wildcarded files

[Peter Maydell <peter.maydell@linaro.org>]

On 30 October 2018 at 12:50, Peter Maydell <peter.maydell@linaro.org> wrote:
> This patchset fixes a problem with our build infrastructure
> that meant that MST's recent 'pci, pc, virtio' pullreq failed
> tests.
>
> Currently our configure script has a wildcard loop that creates
> symlinks for every data file in tests/acpi-test-data from the
> source tree to the build tree. However, if a new data file is
> added in git, there is nothing that causes configure to be rerun,
> and so it is not available in the build tree, which can cause
> test failures.
>
> The core of the change here is that instead of linking every
> individual data file, we just symlink the directory itself (which
> we do in patch 2 for this and also tests/hex-loader-check-data).
> The rest of the patchset deals with:
>  * renaming a shell variable to make it clearer that it's OK
>    to put directories to symlink in it, not just files
>  * adding a comment about why wildcarding is a bad idea
>  * cleaning up a couple of places that did their own symlinking
>    when they could have just used the existing code
>
> We do still use wildcarding to construct a list of files in
> pc-bios to be symlinked; we get away with this because we don't
> in practice add new BIOS images often and if we do there's also
> usually a change that means configure is rerun anyway. We can't
> just symlink all of pc-bios into the build tree because it
> contains other things than just generated binaries. There's
> scope for fixing this, I think, but I wanted to get this fix out.

...having sent this out and moved on to something else, I have
discovered a problem with it. If you configure a build tree
using this, and then switch back to a git branch which has
the older configure, then that configure will end up trashing
all the tests/acpi-test-data and tests/hex-loader-check-data
files in the source tree by replacing them with symlinks to
themselves... This is fixable by doing "git checkout tests"
but it's a bit of a landmine for bisection :-(

thanks
-- PMM