From mboxrd@z Thu Jan  1 00:00:00 1970
From: Maxime Coquelin <maxime.coquelin@redhat.com>
Subject: Re: [PATCH 2/6] vhost: get guest/host physical address
	mappings
Date: Tue, 23 Aug 2016 15:25:33 +0200
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To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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On 08/23/2016 02:32 PM, Yuanhan Liu wrote:
>>> +
>>> > >+	/* FIXME */
>>> > >+	RTE_LOG(INFO, VHOST_CONFIG, ":: %u ::\n", pre_read);
>> > For my information, what is the purpose of pre_read?
> Again, I put a FIXME here, but I forgot to add some explanation.
>
> Here is the thing: the read will make sure the kernel populate the
> corresponding PTE entry, so that rte_mem_virt2phy() will return proper
> physical address, otherwise, invalid value is returned.
>
> I can't simply do the read but do not actually reference/consume it.
> Otherwise, the compiler will treat it as some noops and remove it.
>
> An ugly RTE_LOG will make sure the read operation is not eliminated.
> I'm seeking a more proper way to achieve that. Maybe I can add a new
> field in virtio_net structure and store it there.
>
> Or, do you have better ideas?

This behavior is pretty twisted, no?
Shouldn't be rte_mem_virt2phy() role to ensure returning a valid value?

I have no better idea for now, but I will think about it.

Regards,
Maxime