[Xenomai-core] Re: [PATCH] Shared interrupts (ready to merge)

[Dmitry Adamushko <dmitry.adamushko@domain.hid>]

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On 16/02/06, Jan Kiszka <jan.kiszka@domain.hid> wrote:

Hmm, I still find XN_ISR_NOINT in the patch. Shouldn't we solve this
> before merging (i.e. make XN_ISR_HANDLED non-zero)?


Ok, XN_ISR_NOINT is removed in favor of XN_ISR_HANDLED which is now
non-zero.
Actually, at first I wanted to make it just the other way about.


Moreover, I attached an add-on patch to overcome the name buffer in
> xnintr_t. Note that this patch is only compile-tested, I have no native
> interrupt test-case at hand.



Heh.. someone once suggested the -p key with "diff" to me? :o)

I bet your patch would even work but it's, well, slightly broken indeed ;-)

Look at the native/syscall.c : __rt_intr_delete() :

RT_INTR *intr = (RT_INTR *)rt_registry_fetch(ph.opaque);
...
xnfree(intr);

"intr" actually points to intr_buf->intr and it works as expected only
because "RT_INTR intr" is the first member of the struct, so that it's
address == the address of the whole object of this struct.

To do it properly you would need to make your "unnamed" struct visible
for both __rt_intr_create() and __rt_intr_delete(). Something like :

struct RT_INTR_ENV {

#define link2intr_env(laddr) \
((RT_INTR_ENV *)(((char* )laddr) - (int)(&((RT_INTR_ENV *)0)->intr)))

    RT_INTR intr;
    char name[XNOBJECT_NAME_LEN];
};

and then make use of link2intr_env() in __rt_intr_delet().


Ok, with you approach we would avoid allocating memory
for name[XNOBJECT_NAME_LEN] when an object is created in kernel-mode
and do it via RT_INTR_ENV only when it's created in user-mode.

We could even use that approach for all objects in native skin, but we can't
because of "anonymous" objects supported in kernel-mode too and, well, I
personally would not like those RT_OBJECT_ENV structures all over the map in
syscall.c :)

So I don't want to break the whole picture only for the RT_INTR object (it
doesn't support "anonymous" objects now).

Nevertheless, if you still want to save a hundred bytes of data or so (how
many interrupt objects would a normal system have? and I guess the lenght of
name is about 10 symbols on average :)

for the users that don't use native skin, then I would suggest the following
way :

xnintr_t contains just the link "char *name" as you suggested but RT_INTR
contains the name[XNOBJECT_NAME_LEN] member (as it was before actually).

If it's ok,  then I'll send um... yet another final patch that addresses
both issues :)


Jan
>
>
>

--
Best regards,
Dmitry Adamushko

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