Messages in this thread | | | Date | Mon, 6 Feb 2012 12:02:24 -0500 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [PATCH] xen/tmem: cleanup |
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On Mon, Feb 06, 2012 at 04:49:42PM +0000, Jan Beulich wrote: > >>> On 06.02.12 at 17:37, Dan Magenheimer <dan.magenheimer@oracle.com> wrote: > >> From: Jan Beulich [mailto:JBeulich@suse.com] > >> Sent: Monday, February 06, 2012 1:13 AM > >> To: Dan Magenheimer > >> Cc: Jeremy Fitzhardinge; xen-devel@lists.xensource.com; Konrad Wilk; > > linux-kernel@vger.kernel.org > >> Subject: RE: [PATCH] xen/tmem: cleanup > >> > >> >>> On 04.02.12 at 17:42, Dan Magenheimer <dan.magenheimer@oracle.com> wrote: > >> >> From: Jan Beulich [mailto:JBeulich@suse.com] > >> >> Subject: [PATCH] xen/tmem: cleanup > >> >> > >> >> Use 'bool' for boolean variables. Do proper section placement. > >> >> Eliminate an unnecessary export. > >> >> > >> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > >> >> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> > >> >> > >> >> -int tmem_enabled __read_mostly; > >> >> -EXPORT_SYMBOL(tmem_enabled); > >> >> +bool __read_mostly tmem_enabled = false; > >> > > >> > tmem_enabled is used in xen/drivers/xen-selfballoon.c > >> > >> Which can't be built as a module, and hence the symbol doesn't need > >> exporting. This patch (of course, I'm tempted to say) survived build > >> testing. > > > > Yes, correct. BUT... I think only the reason xen-selfballoon.c > > can't be built as a module is because the MM variable vm_committed_as > > (or an access function) is not exported. Ideally xen-selfballoon.c > > probably should be a module but putting a core MM change in > > the critical path of a Xen-only-related enhancement seemed > > a recipe for sure failure. > > No, this isn't the main reason (as you say further down, this could > easily be adjusted for) afaict. The main reason is that > register_xen_selfballooning() is being called from non-modular > code (xen-balloon.c), which could be made a module too, but in > turn has at least one reference that wouldn't be nice to become > an export (balloon_set_new_target()).
It would be nice if all of it could become modules. That way HVM device driver domains could load the whole thing without having much built-in code in the kernel.
Is it possible to do that? > > Jan > > > Konrad, if you (1) disagree entirely, or (2) want to remove the > > tmem_enabled EXPORT_SYMBOL now and add it back later if/when > > the core MM change happens, I'll leave that up to you. > > > > If (2), the MM change should be added to the minor-tmem-related- > > changes-that-need-to-be-eventually-upstreamed list ;-) > > > > Dan > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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