Re: gpart destroy efi partition?

On Tue, May 23, 2023 at 04:43:52AM -0600, Warner Losh wrote:
> On Mon, May 22, 2023, 10:35 PM Steve Kargl <sgk@troutmask.apl.washington.edu>
> wrote:
> 
> > On Mon, May 22, 2023 at 09:51:40PM -0600, Warner Losh wrote:
> > > On Mon, May 22, 2023, 9:45 PM Steve Kargl <
> > sgk@troutmask.apl.washington.edu>
> > > wrote:
> > >
> > > > Is there a secret incantation for destroying an EFI
> > > > partition on a USB memstick?  After installing FreeBSD,
> > > > I would like to re-use a memstick, but
> > > >
> > > > % gpart destroy da0
> > > > gpart: geom 'da0': Read-only file system
> > > > % gpart destroy -F da0
> > > > gpart: geom 'da0': Read-only file system
> > > > % gpart show da0
> > > > =>      40  60063664  da0  GPT  (29G)
> > > >         40  60063664    1  ms-basic-data  (29G)
> > > > % gpart delete -i 1 da0
> > > > gpart: geom 'da0': Read-only file system
> > > > % dd if=/dev/zero of=/dev/da0 bs=1m
> > > > dd: /dev/da0: Read-only file system
> > > >
> > >
> > > What's mounted?
> > >
> >
> > Nothing mounted other than the boot partition on
> > an internal hard drive.  I plugged the memstick into
> > a usb port, and use gpart to list disk info.
> >
> > % df
> > Filesystem  1M-blocks  Used  Avail Capacity  Mounted on
> > /dev/ada0p2    458231 62032 359539    15%    /
> > devfs               0     0      0     0%    /dev
> >
> > ada0p1 is the EFI boot partition on the internal drive.
> > ada0p3 is swap.
> >
> > % gpart list da0
> > Geom name: da0
> > modified: false
> > state: OK
> > fwheads: 255
> > fwsectors: 63
> > last: 60063703
> > first: 40
> > entries: 128
> > scheme: GPT
> > Providers:
> > 1. Name: da0p1
> >    Mediasize: 30752595968 (29G)
> >    Sectorsize: 512
> >    Stripesize: 0
> >    Stripeoffset: 20480
> >    Mode: r0w0e0
> >    efimedia: HD(1,GPT,a2e07858-a4b6-11ec-ac6a-fcaa142bc587,0x28,0x3947fb0)
> >    rawuuid: a2e07858-a4b6-11ec-ac6a-fcaa142bc587
> >    rawtype: ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
> >    label: (null)
> >    length: 30752595968
> >    offset: 20480
> >    type: ms-basic-data
> >    index: 1
> >    end: 60063703
> >    start: 40
> > Consumers:
> > 1. Name: da0
> >    Mediasize: 30752636928 (29G)
> >    Sectorsize: 512
> >    Mode: r0w0e0
> >
> > I did find
> >
> > % sysctl -a | grep da01
> > kern.geom.disk.da0.flags:
> > 1a8<CANFLUSHCACHE,DIRECTCOMPLETION,CANZONE,WRITEPROTECT>
> >
> > So, I suppose the question is how to clear WRITEPROTECT.
> >
> 
> Assuming you are running as root...
> 
> WRITEPROTECT gets set when we do a MODE SENSE of the disk when we're
> probing it. That returns a status that indicates that the device is
> indicating it is write protected. So we set the write_protect flags in the
> disk structure which is what's reported above and used to generate the read
> only errors.
> 
> if you are lucky, this is a software write protect. That's on mode page
> 0xa. camcontrol can read that:
> # camcontrol modepage da0 -m 0xa
> will report it. if SWP is 1, then it's a software lock. Add -e to the
> above to edit it and change the line with  SWP on it from  1->0 and save.
> this will set the current value, turning it off temporarily. You can then
> proceed to write to the device, with luck.
> 
> Without  luck the drive encountered a condition that made it decide to lock
> you out forever from  writing again.

Thanks for the advice, Warner.  I thought about camcontrol
last night, but it's been a long long time since I've had 
a need for it.

% camcontrol modepage da0 -l
0x08    Caching
0x1c    Informational Exceptions Control
0x05    Flexible Disk
% camcontrol modepage da0 -m 0xa
camcontrol: mode sense command returned error

I suppose this is the end for that memstick.
-- 
Steve