DOKK / manpages / debian 12 / libnvme-dev / nvme_id_ctrl_vwc.2.en
libnvme(2) API Manual libnvme(2)

enum nvme_id_ctrl_vwc - Volatile write cache

enum nvme_id_ctrl_vwc {
NVME_CTRL_VWC_PRESENT ,
NVME_CTRL_VWC_FLUSH

};

If set, indicates a volatile write cache is present. If a volatile write cache is present, then the host controls whether the volatile write cache is enabled with a Set Features command specifying the value NVME_FEAT_FID_VOLATILE_WC.
Mask to get the value of the flush command behavior.
enum nvme_id_ctrl_vwc January 2023