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Re: [PATCH V4 14/24] arm/ioreq: Introduce arch specific bits for IOREQ/DM features

On 27.01.21 12:24, Jan Beulich wrote:

Hi Jan

On 21.01.2021 09:50, Oleksandr wrote:
On 20.01.21 17:50, Julien Grall wrote:
On 17/01/2021 18:52, Oleksandr wrote:
error2.txt - when add #include <public/hvm/dm_op.h> to xen/ioreq.h
It looks like the error is happening in dm.c rather than xen/dm.h. Any
reason to not include <public/hvm/dm_op.h> in dm.c directly?
Including it directly doesn't solve build issue.
If I am not mistaken in order to follow requirements how to include
headers (alphabetic order, public* should be included after xen* and
asm* ones, etc)
the dm.h gets included the first in dm.c, and dm_op.h gets included the
last. We can avoid build issue if we change inclusion order a bit,
what I mean is to include dm.h after hypercall.h at least (because
hypercall.h already includes dm_op.h). But this breaks the requirements
and is not way to go.
Now I am in doubt how to overcome this.
First, violating the alphabetic ordering rule is perhaps less
of a problem than putting seemingly stray #include-s anywhere.
However, as soon as ordering starts mattering, this is
indicative of problems with the headers: Either the (seemingly)
too early included one lacks some #include-s, or you've run
into a circular dependency. In the former case the needed
#include-s should be added, and all ought to be fine. In the
latter case, however, disentangling may be a significant
effort, and hence it may be sensible and acceptable to instead
use unusual ordering of #include-s in the one place where it
matters (suitably justified in the description). Ideally such
would come with a promise to try to sort this later on, when
time is less constrained.
Thank you for the explanation. I think, I am facing the former case (too early included one lacks some #include-s),
actually both common/dm.c and arch/arm/dm.c suffer from that.
It works for me if I add the following to both files (violating the alphabetic ordering rule):

+#include <xen/types.h>
+#include <public/hvm/dm_op.h>
 #include <xen/dm.h>

So, if I got your point correctly, we could include these both headers by dm.h) Would it be appropriate (with suitable justification of course)? I think, we could avoid including xen/sched.h by dm.h (need to recheck), just these two headers above.



Oleksandr Tyshchenko



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