On 8/4/20 12:12 PM, Stefan Hajnoczi wrote: > Make it possible to present read-only files to the guest as "unarmed" > NVDIMMs. The Linux NVDIMM device (/dev/pmemX) is read-only. > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > --- > docs/nvdimm.txt | 8 +++++++- > hw/mem/nvdimm.c | 4 ++++ > 2 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt > index c2c6e441b3..c0b52de111 100644 > --- a/docs/nvdimm.txt > +++ b/docs/nvdimm.txt > @@ -17,7 +17,7 @@ following command line options: > > -machine pc,nvdimm > -m $RAM_SIZE,slots=$N,maxmem=$MAX_SIZE > - -object > memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE > + -object > memory-backend-file,id=mem1,share=on,mem-path=$PATH,size=$NVDIMM_SIZE,readonly=off > -device nvdimm,id=nvdimm1,memdev=mem1 > > Where, > @@ -42,6 +42,12 @@ Where, > "share=off", then guest writes won't be applied to the backend > file and thus will be invisible to other guests. > > + "readonly=on/off" controls whether the the file $PATH is opened read-only > or
Double "the the". > + read/write (default). "readonly=on" sets the ACPI NFIT NVDIMM Region > Mapping NFIT acronym for 'NVDIMM Firmware Interface Table', "NVDIMM" sounds redundant but makes it easier to understand, so OK. > + Structure "NVDIMM State Flags" Bit 3 indicating that the device is > "unarmed" > + and cannot accept persistent writes. Linux guest drivers set the device to > + read-only when this bit is present. > + > - "device nvdimm,id=nvdimm1,memdev=mem1" creates a virtual NVDIMM > device whose storage is provided by above memory backend device. > > diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c > index e1574bc07c..694223450e 100644 > --- a/hw/mem/nvdimm.c > +++ b/hw/mem/nvdimm.c > @@ -151,6 +151,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice > *nvdimm, Error **errp) > "nvdimm-memory", mr, 0, pmem_size); > memory_region_set_nonvolatile(nvdimm->nvdimm_mr, true); > nvdimm->nvdimm_mr->align = align; > + > + if (memory_region_is_rom(mr)) { > + nvdimm->unarmed = true; /* this device is read-only */ > + } Can you move this hunk before the alias creation? (Just before nvdimm->nvdimm_mr = ...). > } > > static MemoryRegion *nvdimm_md_get_memory_region(MemoryDeviceState *md, I don't understand why MemoryDeviceClass::get_memory_region() implicitly calls DeviceClass::realize()... Anyway unrelated to this patch. With the comments addressed: Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>