From: Tamas Lengyel <tamas.lengyel@zentific.com>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Aravindh Puthiyaparambil <aravindp@cisco.com>,
Ian Jackson <Ian.Jackson@eu.citrix.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: Issues regarding "mem_access: Add helper API to setup ring and enable mem_access"
Date: Mon, 30 Jun 2014 14:06:24 +0200 [thread overview]
Message-ID: <CAErYnsgxODtiWNR2y+dmQooHahd9s=X+aFr3pZik8n9jV6_9Zg@mail.gmail.com> (raw)
In-Reply-To: <1403882455.3169.72.camel@kazak.uk.xensource.com>
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> > Now with this function being reintroduced, it becomes more complicated
> > to determine which version of the mem_access API does Xen actually
> > provide. A #define indicating mem_access API version would nicely
> > overcome this issue, or naming xc_mem_event_enable something else.
>
> Doesn't configure support checking for functions with a given prototype?
>
It does but in a very hacky way, essentially trying to compile code where
the function is being called with different prototypes. We can work around
it but a clean solution would be preferred at some point.
> > Furthermore, the new xc_mem_event_enable function unconditionally
> > unpauses the VM. This may not be a desired behavior in all cases,
> > especially if the VM was in a paused state when the function was
> > called.
>
> domain pauses are referenced counted on the hypervisor side.
>
> Ian.
>
>
I did a quick test with xc_domain_pause being called twice, then
xc_domain_unpause once and the domain was in unpaused state at the end.
Same with the xen-access example, a paused domain gets automatically
unpaused by libxc, either though the xen-access code doesn't specifically
say it should be. This is now a rather opaque behavior of libxc. As it is
not merged into master I guess I will just submit a patch for it..
Tamas
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next prev parent reply other threads:[~2014-06-30 12:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 16:31 Issues regarding "mem_access: Add helper API to setup ring and enable mem_access" Tamas Lengyel
2014-06-27 15:20 ` Ian Campbell
2014-06-30 12:06 ` Tamas Lengyel [this message]
2014-06-30 12:42 ` Ian Jackson
2014-06-30 12:44 ` Ian Campbell
2014-06-30 13:07 ` Andrew Cooper
2014-06-30 13:09 ` Ian Campbell
2014-06-30 13:10 ` Andrew Cooper
2014-06-30 14:12 ` Jan Beulich
2014-06-30 14:19 ` Andrew Cooper
2014-06-30 14:49 ` Tamas Lengyel
2014-06-30 22:14 ` Aravindh Puthiyaparambil (aravindp)
2014-06-30 22:31 ` Aravindh Puthiyaparambil (aravindp)
2014-07-02 11:54 ` Tamas Lengyel
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