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 <[email protected]> --- 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 + read/write (default). "readonly=on" sets the ACPI NFIT NVDIMM Region Mapping + 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 */ + } } static MemoryRegion *nvdimm_md_get_memory_region(MemoryDeviceState *md, -- 2.26.2
