Re: how to remove freebsd when it is running

On 4/17/24 07:21, hlyg wrote:
> my freebsd 13 is installed at flash disk of dell thin client
> 
> it doesn't work well, i want to remove it
> 
> "dd if=/dev/zero of=/dev/ada0 count=1000 ..." doesn't work, freebsd 
> doesn't allow

If I recall, writing directly to a disk that is otherwise mounted is 
disabled by default; geom(4) describes setting kern.geom.debugflags=10 
to alter that.

> according to dell manual, i shall be able to enter bios by pressing F2 
> before bsd booting so that i can set boot sequence  to boot from usb 
> disk, but i can't enter bios, pressing F2 doesn't work

   The ability to press a key can be altered in some BIOS 
configurations. F12 is an alternative on many Dell computers to go to a 
menu which should offer going to BIOS once it comes up. Either key 
should be repeatedly tapped just after power on until you get the screen 
you want or the OS boot loader has been reached or passed; I do not 
recall seeing a Dell computer that required it be held, nor one that 
would not enter BIOS if tapping too soon. I commonly just tap F1, F2, 
F10, and delete to get into BIOS though there are machines with setups 
requiring F7, F8, F10, Esc, etc. to get in, get to a menu, or 
temporarily choose the boot device directly.

   "If" your keyboard has a modifier like fn key then you 'may' need to 
press it in combination with the BIOS key Some keyboards do not always 
start fast enough to enter BIOS; try connecting the keyboard direct to 
the computer instead of a USB hub and try different ports on the back as 
USB2 vs 3 can make a difference and which USB chipset it is on can too.

> it's not easy for me to open case and dismount disk
> 
>