Hi Jassi,
On Tue, 19 Jul 2022 at 18:27, Jassi Brar <jaswinder.si...@linaro.org> wrote:
>
> On Mon, 18 Jul 2022 at 16:00, Tom Rini <tr...@konsulko.com> wrote:
> > On Mon, Jul 18, 2022 at 10:31:56AM -0500, Jassi Brar wrote:
>
> > > > > > >
> > > > > > > > > +
> > > > > > > > > +#define PLAT_METADATA_OFFSET 0x510000
> > > > > > > > > +#define PLAT_METADATA_SIZE (sizeof(struct devbox_metadata))
> > > > > > > > > +
> > > > > > > > > +struct __packed devbox_metadata {
> > > > > > > > > + u32 boot_index;
> > > > > > > > > + u32 boot_count;
> > > > > > > >
> > > > > > > > There is the whole bootcount infrastructure for this. I think
> > > > > > > > it would be much
> > > > > > > > better to use that framework instead of creating parallel one.
> > > > > > > >
> > > > > > > Yes, this goes too.
> > > > > >
> > > > > > Is bootcount really suited for this case?
> > > > > > AFAIK bootcount either requires device specific registers (which
> > > > > > won't
> > > > > > reset on reboots), or an environment you can write data to.
> > > > > > But what if a user wants to disable writing the env variables and
> > > > > > the
> > > > > > device doesn't have a set of registers we can use?
> > > > > >
> > > > > Maybe it should be moved in 'struct fwu_mdata' ?
> > > >
> > > > I was mostly thinking on moving this count as another 'bootcount'
> > > > method. So in case the user has disabled writing evn variables but he
> > > > is booting with EFI he can use that.
> > >
> > > Sorry, not sure I understand.... IIUIC there has to be some persistent
> > > storage.
> >
> > No, there just has to be "somewhere" to do the counting. We've got a
> > DDR backed driver, for example. So yes, I think we should try and use
> > the bootcount framework here.
> >
> OK, for platforms that can preserve ram across reboot, using
> non-persistent storage can work.
> My platform neither preserves ram, nor has any warmreset-proof
> registers. So I have to choose between saving the bootcount in efi-env
> or in vendor specific structure next to the metadata. I prefer
> metadata because it is common to all stages of boot. Any corrections
> to this approach?
The metadata is defined by a spec and they don't have a field for
bootcounting. Once Sughosh resends his patches he'll include a
bootcount backend that reuses EFI variables. Can't we just use that?
>
> Thanks
