Re: [XEN PATCH 02/15] build: rework asm-offsets.* build step to use kbuild

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, May 24, 2023 at 04:09:39PM +0200, Jan Beulich wrote:
> On 23.05.2023 18:37, Anthony PERARD wrote:
> > Use $(if_changed_dep, ) macro to generate "asm-offsets.s" and remove
> > the use of $(move-if-changes,). That mean that "asm-offset.s" will be
> > changed even when the output doesn't change.
> > 
> > But "asm-offsets.s" is only used to generated "asm-offsets.h". So
> > instead of regenerating "asm-offsets.h" every time "asm-offsets.s"
> > change, we will use "$(filechk, )" to only update the ".h" when the
> > output change. Also, with "$(filechk, )", the file does get
> > regenerated when the rule change in the makefile.
> > 
> > This changes also result in a cleaner build log.
> > 
> > Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> > ---
> > 
> > Instead of having a special $(cmd_asm-offsets.s) command, we could
> > probably reuse $(cmd_cc_s_c) from Rules.mk, but that would mean that
> > an hypothetical additional flags "-flto" in CFLAGS would not be
> > removed anymore, not sure if that matter here.
> 
> There's no real code being generated there, and what we're after are
> merely the special .ascii directives. So the presence of -flto should
> have no effect there, and hence it would even look more consistent to
> me if we didn't use different options (and even rules) for .c -> .s
> transformations.
> 
> > But then we could write this:
> > 
> > targets += arch/$(TARGET_ARCH)/$(TARGET_SUBARCH)/asm-offsets.s
> > arch/$(TARGET_ARCH)/$(TARGET_SUBARCH)/asm-offsets.s: CFLAGS-y += -g0
> > arch/$(TARGET_ARCH)/include/asm/asm-offsets.h: 
> > arch/$(TARGET_ARCH)/$(TARGET_SUBARCH)/asm-offsets.s FORCE
> > 
> > instead of having to write a rule for asm-offsets.s
> 
> Ftaod, I'd be happy to ack the patch as it is, but I would favor if
> you could do the rework / simplification as outlined.

Thanks, I'll do this rework.

-- 
Anthony PERARD