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Subject: Re: [PATCH RFC v4 00/13] virtio-mem: paravirtualized memory
To:     Alex Shi <alex.shi@linux.alibaba.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>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        Sebastien Boeuf <sebastien.boeuf@intel.com>,
        Samuel Ortiz <samuel.ortiz@intel.com>,
        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>,
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        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>
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From:   David Hildenbrand <david@redhat.com>
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Message-ID: <b41dcc92-604e-0c48-92e5-5cb3d78f189e@redhat.com>
Date:   Fri, 5 Jun 2020 14:18:28 +0200
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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

(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.

-- 
Thanks,

David / dhildenb