Re: [Xen-devel] [PATCH] xen: convert lto to Kconfig option

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Dec 05, 2016 at 08:05:35AM -0700, Jan Beulich wrote:
> >>> On 05.12.16 at 15:39, <wei.liu2@xxxxxxxxxx> wrote:
> > Introduce CONFIG_LTO in Kconfig. Since this is the last option to be
> > converted to Kconfig, delete the preceding comment in Rules.mk as well.
> > 
> > Make it depend on BROKEN because it doesn't work at the moment.
> 
> Looks fine except for this one aspect: Is that brokenness with gcc,
> clang, or both? I wouldn't be surprised if it was broken with gcc (in

It's going to be both.

Its build rune is broken.

I got:

  head.S:212:0: fatal error: opening dependency file /..d: Permission denied

That is, this rule

  CFLAGS-y += -MMD -MF $(@D)/.$(@F).d                                           
  

is evaluated too early outside of prerequisite list, which results in
empty string.

Also I'm sure gcc can't deal with lto because at one point I tried to
fix lto but gcc  toolchain can't cope with that.

> fact I would be surprised it has ever worked), but I would have
> hoped that the clang variant (which iirc this was introduced for)
> would work (also e.g. in 4.8).
> 

I haven't tried clang, because the brokenness is somewhere else.

Wei.

> Jan
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel