Re: Lost partition tables on ide-hd + ahci drive

[Mike Maslenkin <mike.maslenkin@gmail.com>]

Makes sense for disks without partition table.
But wouldn't Linux or any other OS write at least 4K bytes in that case?
Who may want to write 512 bytes for any purposes except for boot
sector nowadays..
In dump mentioned before only 512 bytes were not zeroed, so I guess it
was caused by IO from guest OS.
In other cases it can be caused by misconfigured IDE registers state
or broken FIS memory area.


On Thu, Feb 16, 2023 at 6:25 PM Fiona Ebner <f.ebner@proxmox.com> wrote:
>
> Am 16.02.23 um 15:17 schrieb Mike Maslenkin:
> > Does additional comparison make a sense here: check for LBA == 0 and
> > then check MBR signature bytes.
> > Additionally it’s easy to check buffer_is_zero() result or even print
> > FIS contents under these conditions.
> > Data looks like a part of guest memory of 64bit Windows.
>
> Thank you for the suggestion! I'll think about adding such a check and
> dumping of FIS contents in a custom build for affected users. But in
> general it would be too much noise for non-MBR cases: e.g. on a disk
> formatted with ext4 (without any partitions), Linux will write to sector
> 0 on every startup and shutdown.
>
> Best Regards,
> Fiona
>