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Subject: Re: [PATCH RFC v4 00/13] virtio-mem: paravirtualized memory
To:     David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, virtio-dev@lists.oasis-open.org,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        Michal Hocko <mhocko@kernel.org>,
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        "Michael S . Tsirkin" <mst@redhat.com>,
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        Robert Bradford <robert.bradford@intel.com>,
        Luiz Capitulino <lcapitulino@redhat.com>,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        Alexander Potapenko <glider@google.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Anthony Yznaga <anthony.yznaga@oracle.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Young <dyoung@redhat.com>,
        Igor Mammedov <imammedo@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Juergen Gross <jgross@suse.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Len Brown <lenb@kernel.org>,
        Mel Gorman <mgorman@techsingularity.net>,
        Michal Hocko <mhocko@suse.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Oscar Salvador <osalvador@suse.com>,
        Oscar Salvador <osalvador@suse.de>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Pavel Tatashin <pavel.tatashin@microsoft.com>,
        Pingfan Liu <kernelfans@gmail.com>, Qian Cai <cai@lca.pw>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Wei Yang <richard.weiyang@gmail.com>
References: <20191212171137.13872-1-david@redhat.com>
 <9acc5d04-c8e9-ef53-85e4-709030997ca6@redhat.com>
 <1cfa9edb-47ea-1495-4e28-4cf391eab44c@linux.alibaba.com>
 <d6cd1870-1012-cb3d-7d29-8e5ad2703717@redhat.com>
 <6b4724bf-84b5-9880-5464-1908425d106d@redhat.com>
 <e1643897-ebd7-75f8-d271-44f62318aa66@redhat.com>
 <95c6ef21-23e0-c768-999d-3af7f69d02d3@linux.alibaba.com>
 <b41dcc92-604e-0c48-92e5-5cb3d78f189e@redhat.com>
From:   Alex Shi <alex.shi@linux.alibaba.com>
Message-ID: <acf6c8d5-9672-7ec8-f565-707aaaff8e48@linux.alibaba.com>
Date:   Tue, 9 Jun 2020 11:05:50 +0800
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在 2020/6/5 下午8:18, David Hildenbrand 写道:
> On 05.06.20 12:46, Alex Shi wrote:
>>
>>
>> 在 2020/6/5 下午6:05, David Hildenbrand 写道:
>>>> I guess I know what's happening here. In case we only have DMA memory
>>>> when booting, we don't reserve swiotlb buffers. Once we hotplug memory
>>>> and online ZONE_NORMAL, we don't have any swiotlb DMA bounce buffers to
>>>> map such PFNs (total 0 (slots), used 0 (slots)).
>>>>
>>>> Can you try with "swiotlb=force" on the kernel cmdline?
>>> Alternative, looks like you can specify "-m 2G,maxmem=16G,slots=1", to
>>> create proper ACPI tables that indicate hotpluggable memory. (I'll have
>>> to look into QEMU to figure out to always indicate hotpluggable memory
>>> that way).
>>>
>>
>>
>> That works too. Yes, better resolved in qemu, maybe. :)
>>
> 
> You can checkout
> 
> git@github.com:davidhildenbrand/qemu.git virtio-mem-v4

yes, it works for me. Thanks!

> 
> (prone to change before officially sent), which will create srat tables
> also if no "slots" parameter was defined (and no -numa config was
> specified).
> 
> Your original example should work with that.
>