[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [XEN PATCH v3 16/23] xen/build: introduce if_changed and if_changed_rule

On 18.03.2020 11:44, Anthony PERARD wrote:
On Wed, Mar 04, 2020 at 04:45:36PM +0100, Jan Beulich wrote:
On 26.02.2020 12:33, Anthony PERARD wrote:
The if_changed macro from Linux can record the command used to build a
target then compare it on rebuild. Thus if a command has changed, for
example due to introducing new flags in CFLAGS or due to using a
different compiler, the target will be rebuilt.

As to using a different compiler - I suppose this means "a compiler
with a different executable name" here? What about me having, say
gcc-5 in use, and then updating my system such that a 5.2 based
compiler of this name would be upgraded to a 5.4 based one of this
same name. If this newer compiler has better capabilities (that we
would want to use if available), would this or anything else trigger
a rebuild then too?

I think I should have written "command line" instead of just "command".
When writing about "different compiler" I was mostly thinking about GCC
vs clang, not really about versions. I think Linux has something that
detects when the compiler version changes, but that maybe to only
trigger kconfig, to regenerate the .config file.

But as you say, if the newer compiler has better capabilities, and the
*FLAGS are changed, then that would trigger a rebuild if other
dependency hasn't changed.

"Would" as in "would", or merely "it would be nice if it did"? I'm
simply not seeing where such a detection would be happening.


Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.