Re: [Xen-devel] [PATCH v6 08/15] x86/efi: create new early memory allocator

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.09.16 at 14:07, <daniel.kiper@xxxxxxxxxx> wrote:
> On Thu, Sep 22, 2016 at 05:25:46AM -0600, Jan Beulich wrote:
>> >>> On 22.09.16 at 12:52, <daniel.kiper@xxxxxxxxxx> wrote:
>> > On Wed, Sep 21, 2016 at 03:42:09AM -0600, Jan Beulich wrote:
>> >> >>> On 20.09.16 at 20:45, <daniel.kiper@xxxxxxxxxx> wrote:
>> >> > On Tue, Sep 20, 2016 at 07:46:56AM -0600, Jan Beulich wrote:
>> >> >> >>> On 20.09.16 at 12:52, <daniel.kiper@xxxxxxxxxx> wrote:
>> >
>> > [...]
>> >
>> >> >> > Do you suggest that I should move out of #ifndef CONFIG_ARM all 
>> >> >> > ebmalloc
>> > stuff
>> >> >> > except free_ebmalloc_unused_mem(). Even if it is not used on ARM 
>> >> >> > right
>> > now?
>> >> >>
>> >> >> That's not the static function, is it? The function you name should
>> >> >> actually be called on ARM too (as I did point out elsewhere already),
>> >> >> just to not leave a trap open for someone to fall into when (s)he
>> >> >> adds a first use of the allocator on ARM.
>> >> >
>> >> > Well, I think that sane person doing that would analyze how ebmalloc 
>> >> > works
>> >> > on x86 and then move (align to ARM needs if required) all its machinery
>> >> > (including free_ebmalloc_unused_mem()) to run on ARM. At least I would 
>> >> > do
>> >> > that. This way he/she would avoid issues mentioned by you. However, if 
>> >> > you
>> >> > still prefer your way I can do that. Though I am not sure about the 
>> >> > rest 
> of
>> >> > ebmalloc stuff. Should I move it out of #ifndef CONFIG_ARM? Looking at 
> your
>> >> > earlier replies I see that yes. Am I correct?
>> >>
>> >> Yes.
>> >
>> > This does not work because if I build Xen for ARM then I got:
>> > boot.c:589:21: error: 'ebmalloc' defined but not used
>> > [-Werror=unused-function]
>> >  static void __init *ebmalloc(size_t size)
>>
>> Quote from an earlier reply of mine:
>>
>>   Arguably the one static function may better be, as other
>>   workarounds to avoid the "unused" compiler warning wouldn't
>>   be any better.
>>
>> and then later
>>
>>   You misunderstood - I said that for this one (unused) static
>>   function such an #ifdef is probably okay, as the presumably
>>   smallest possible workaround.
>>
>> I really have no idea what else to say.
> 
> Sorry, however, sometimes it is very difficult to understand what are
> you referring to. If you could be more specific then I will be happy.
> 
> Anyway, now it looks that you wish something like that:
> 
> #ifndef CONFIG_ARM
> /* Whole x86 ebmalloc stuff. */
> ...
> #else
> void __init free_ebmalloc_unused_mem(void)
> {
> }
> #endif
> 
> and then call free_ebmalloc_unused_mem() from e.g.
> xen/arch/arm/setup.c:init_done(). Am I right?

No. I want the #ifdef to _only_ cover the unused static function.

Jan


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