Re: [Xen-devel] [PATCH] refetch qemu if QEMU_TAG changed

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Fri, 2010-10-29 at 17:12 +0100, Brendan Cully wrote:
> On Friday, 29 October 2010 at 08:20, Ian Campbell wrote:
> > On Fri, 2010-10-29 at 07:57 +0100, Juergen Gross wrote:
> > > Check for a changed QEMU_TAG. If it has changed since last build, delete 
> > > old
> > > qemu sources and refetch with new QEMU_TAG.
> > 
> > Deleteing and recloning seems like an awfully big hammer. Can the same
> > not be achieved with a "git fetch origin" and a "git reset <tag>"?
> 
> In any case, it should probably only do that if the currently
> checked-out version matches the old value of QEMU_TAG and the
> directory has no source modifications, indicating the builder is just
> using the default build. Otherwise it should just warn that QEMU_TAG
> has changed and the ioemu directory may have become out of date.
> 
> With the proposed patch it's very easy to destroy a developer's code.

Quite right, I hadn't considered that aspect.

The following patches adds an explicit update mechanism, which isn't
brilliant but is better than doing "cd tools/ioemu-remote && git reset
--hard <sha1...>" by hand.

For the old hg clone integration for linux-2.6.18-xen.hg (the stuff in
buildconfigs/*) we had XEN_LINUX_UPDATE which forced an update when set
to y. I don't know that was widely used (or indeed known about).

Your suggested warning when the tree differs from the preferred tag
would be a useful and complimentary improvement.

Ian.

diff -r b491f46546d5 -r 7228faad83f5 Makefile
--- a/Makefile  Tue Nov 09 14:12:41 2010 +0000
+++ b/Makefile  Tue Nov 09 14:12:41 2010 +0000
@@ -82,6 +82,10 @@ endif
 
 tools/ioemu-dir:
        $(MAKE) -C tools ioemu-dir-find
+
+.PHONY: tools/ioemu-dir-force-update
+tools/ioemu-dir-force-update:
+       $(MAKE) -C tools ioemu-dir-force-update
 
 .PHONY: install-docs
 install-docs:
diff -r b491f46546d5 -r 7228faad83f5 tools/Makefile
--- a/tools/Makefile    Tue Nov 09 14:12:41 2010 +0000
+++ b/tools/Makefile    Tue Nov 09 14:12:41 2010 +0000
@@ -110,6 +110,14 @@ ioemu-dir-find:
                cd ioemu-dir; \
                ./xen-setup $(IOEMU_CONFIGURE_CROSS)
 
+.PHONY: ioemu-dir-force-update
+ioemu-dir-force-update:
+       set -ex; \
+       if [ "$(QEMU_TAG)" ]; then \
+               cd ioemu-remote; \
+               $(GIT) reset --hard $(QEMU_TAG); \
+       fi
+
 subdir-all-ioemu-dir subdir-install-ioemu-dir: ioemu-dir-find
 
 subdir-clean-ioemu-dir:




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