> Le 22 août 2025 à 17:31, Tom Li via openwrt-devel > <[email protected]> a écrit : > > For OpenWrt routers, writing to NVRAM by default can serve useful > purposes in several contexts: > > 1. Saving a /dev/urandom seed file after boot, to prevent early- > boot entropy starvation in the next boot. This was first discussed > in 2016 [0], and raised again in 2022. [1] > > 2. Saving the last-known system date and time to /etc/dnsmasq.time > for DNSSEC timestep validation, on every SIGTERM and reboot. > Discussed in [2].
On this: « reboot » on most of these devices really means « hard power cycle ». So this seems pretty useless IMHO, since all devices which do clean reboots (e.g. VMs / PCs etc) will already either have RTC or fully writeable fs. > 3. Saving the current IPv6 prefix on the WAN port (obtained from > the ISP) to a file. If the router reboots due to power loss, and > the ISP changes the IPv6 prefix in the next boot, the old prefix > can be invalidated in a Router Advertisements to prevent IPv6 > outages in the LAN due to stale addresses. This is known as "Flash > Renumbering Workaround Across Reboot", a recommended feature by > RFC 9096 to work around broken ISPs. This need is raised in a recent > odhcpd devolopment discussion [3], and is my motivation of sending > this mail. I think this is the most useful feature. If implemented properly, it should result in a single write (per prefix assignment from the ISP, which, for sane ISPs, means only 1) which is no worse than the writes performed during firstboot: it shouldn’t be very controversial. My 2c, T. _______________________________________________ openwrt-devel mailing list [email protected] https://lists.openwrt.org/mailman/listinfo/openwrt-devel
