On Mar 25, 2024, at 13:43, Thomas Cameron <thomas.came...@camerontech.com> 
wrote:
> 
> On 3/25/24 11:38, Patrick O'Callaghan wrote:
>>> On Mon, 2024-03-25 at 11:07 -0500, Thomas Cameron wrote:
>>> dmesg > /dev/nvme1n1
>> What's that about?
>> poc
> 
> To further clarify, my system uses NVMe drives (/dev/nvme0n1 and 
> /dev/nvme1n1). So when I do dmesg > /dev/nvme1n1 as root, it overwrites the 
> first few hundred k of the NVMe disk, nuking the partition tables and boot 
> instructions and the like. Then when I reboot, it causes my machine to PXE 
> boot. You can nuke any drive by writing to the first few sectors, so it could 
> have been /dev/sda, /dev/vda, /dev/xvda, or whatever.

On any modern system that uses UEFI, you can just use “efibootmgr -n ####” to 
temporarily set the next boot target to be the PXE boot entry (which has its 
own unique entry, replace #### with its number). Probably also worth deleting 
the existing entry to boot into Fedora at the same time. 

Wiping the partition table doesn’t always guarantee that the next boot will be 
PXE, which is why I liked to automate it specifically. 

No need to delete or wipe any bootloaders or partition tables, although it 
probably doesn’t hurt. I had a kickstart that preserved custom stuff like the 
krb5 keytab between reloads in the kickstart %pre section, so I didn’t want to 
just nuke the filesystem. 

-- 
Jonathan Billings
--
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