On Thu, Dec 23, 2021 at 1:15 AM Theo de Raadt <dera...@openbsd.org> wrote: > > Crystal Kolipe <kolip...@exoticsilicon.com> wrote: > > > On Tue, Dec 21, 2021 at 06:04:28PM -0500, Rob Whitlock wrote: > > > A problem seems to be that there is no disklabel entry for the ExFAT > > > partition. > > > > You probably wrote a BSD disklabel to the disk before creating the ExFAT partition. > > > > If there is no on-disk disklabel, the kernel will create one in memory based on information from other partitioning schemes, (MBR, GPT). So in this case, as you change those MBR or GPT partitions, those changes will be reflected in the disklabel that the kernel sees. > > > > Once you actually write a disklabel to the disk, that on-disk disklabel is then used in place of calculating one each time the disk is attached, and the automatic parsing of MBR and GPT partition information stops. > > > > To solve your problem, you need to add the details of the ExFAT partition to the BSD disklabel. You can either do that manually with the disklabel command, or since you do not have any OpenBSD partitions on the disk, you could overwrite the on-disk disklabel, allow the kernel to generate one automatically with the correct information, then optionally force it to be written to the disk by running disklabel and entering 'w' at the interactive prompt. > > This can be investigated with > > disklabel -d > > (BTW, when the disklabel is constructed from other information on the disk, > we call it a "spoofed label")
I would like to avoid modifying the data on the disk. Is there a way to use disklabel to update the in-core copy of the disklabel with a spoofed label, without also writing it to disk? I see in the disklabel(5) manual page that the DIOCSDINFO ioctl updates the in-core copy, so it seems it should be technically possible, but I don't see how to do it with the disklabel(8) program. My understanding of disklabel -d is that it gives you a default disklabel to start with, but does not affect how or where the disklabel is written.
