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If you're dealing with a classic 512-bite downloading record, it's pretty simple.DOS-like MBR consists of three parts: the first 446 Byte is directly responsible for the downloader code (bootcode), which is capable of transferring the downloading control to the downloading sector in one of the disk sections; the next 64 Bates describe the " basic " sections of the disc (4 to 16 byte); the remaining 2 bytes is a signature. 55h AAh♪If the loading code was https://gist.github.com/rc5hack/b8f130b4bc1ae26307df somehow damaged, wiped zeros or replaced by another loader who doesn't know anything about FreeBSD, but the tables of the sections stayed on the spot - loaded into one section of FreeBSD can only be used by the loader of any other FreeBSD for start.Start downloading any BSD-like operating system (I checked this method at FreeBSD 6.0, 7.0, 8.0, 8.1, 8.3, 8.4, 9.2 and Frenzy 1.4) from another host, HDD, CD, USB-Flash, through the PXE network, through virtual media through BMC/KVM, etc.In the process of downloading, select the Escape to loader prompt on the downloader screen (it will be under "6" in old FreeBSD, "3" in FreeBSD 9, "8 in Frenzy)Now unload the nucleus ofBSD, which is loaded, and its modules, using the team. unloadFind a disc device on which FreeBSD is located, which needs to be downloaded. disk0s1aUsing a team lsdevChoose this "core" device for the downloader, give the team set currdev="disk0s1a"Read it. loder.conf With your disk (these can be critical to correct khaki loading, like connecting nuclei modules for online maps) by the team. read-conf boot/loader.confAnd finally load your DS with the team. boot-confWhen your inaccessible FreeBSD is downloaded, it'll only be fixed by the loader. In my case, I used it. sysinstallparagraph Custom - constituent Partition, W♪ <Yes>♪ BootMgr "Install the FreeBSD Boot Manager." <OK>♪ Q♪ <Exit>♪ <Exit Install>♪ However, it has been declared obsolete since 9.0-RELEASE ' s withdrawal and removed from the base system since the withdrawal of 10.0-RELEASE. There is also an alternative way to re-establish the loader by using a backup copy stored in /boot Thank you for clues:# gpart bootcode -b /boot/mbr /dev/yourbootdevice