On 25.06.21 г. 19:04 ч., Simon Glass wrote:
Hi Pali,
On Fri, 25 Jun 2021 at 07:07, Pali Rohár <p...@kernel.org> wrote:
On Friday 25 June 2021 08:38:47 Tom Rini wrote:
On Sun, Jun 20, 2021 at 09:43:43PM +0200, Marek Vasut wrote:
On 6/20/21 5:54 PM, Tom Rini wrote:
[...]
As far as I understand, the RX51 has gigabytes of eMMC storage, so it can
use SPL just like any other OMAP3 board.
U-Boot is being called by the old vendor X-Loader fork and needs to take
up the existing flash spot.
So, why not place SPL in those 256 kiB and load U-Boot proper from the eMMC
?
So we need to make
changes in subsystems they use so that they can continue to work.
So, are the changes being proposed to the generic USB code, such that
DM_USB can be enabled, and when DM_USB_GADGET gets a deadline (Note,
that's not set yet, but that's not to say never, it's just not been set,
so getting ahead of problems here would be appreciated) that can also be
enabled, OK?
I am confused by this reply. I noticed a lot of boards were removed over
time because they were not converted to DM/DT, and to get rid of all the
ifdefs, but now it seems the direction has been completely reversed and we
should start adding back all the ifdefs to cater for boards which are not
converted instead of fixing the boards ?
A lot of boards are being removed because no one wants to update and
maintain them and they have likely not been run-time tested in years.
Trying to clean up the code in those cases is best done by removing the
platform, as no one using it. That is not the case here.
Note that there have been boards which had to be switched to SPL to even
permit converting them to DM/DT, and thus prevent removal.
If your only
concern about the approach taken is some #ifdef's in the code, do you
want to see them converted to use some wrapper macro like we do in a few
other cases and __maybe_unused some functions as needed?
I think there is a better option which does not add any ifdefs at all _and_
is future-proof -- place SPL in those 256 kiB, load U-Boot from eMMC and
then enable all the functionality you might need in U-Boot. That would free
you from dealing with the size limitations basically indefinitely.
So, at this point I'm waiting for either of:
- A response to Marek's questions about using SPL, from the Nokia NX51
folks.
Hello Tom! Here is my answer:
So, why not place SPL in those 256 kiB and load U-Boot proper from the eMMC ?
U-Boot for N900 does not use SPL. There is no SPL code implemented.
Nobody ever tried to implement it and neither tested. As you have
correctly pointed instead of SPL is used vendor X-Loader binary, which
is signed by RSA key.
Add eMMC: On eMMC is stored existing operating system, which somehow
also interacts with vendor X-Loader. There was no big investigation on
this topic. Also direct booting from eMMC is not supported (unless you
crack RSA, figure out how secure things work and generate compatible
image) and neither from existing X-Loader (because vendor did not
enabled it). There is no easy access to eMMC until you start full
U-Boot. So even if all these problems are solved then "bootstrapping" or
flashing U-Boot into such location is not possible, plus there is no
recovery. Plus this loose existing and working operating system, which
is no-go. So this way is basically undebugable and therefore perfectly
hard to develop.
I don't want to inject myself in this discussion, although it does
sound like this platform should use SPL. But I do wonder about the
100KB growth you saw with DT/DM. That seems absolutely enormous to me!
Can you please point me to the git tree for this? I'd like to
investigate.
It seems OF_CONTROL pulls everything and the kitchen sink (stuff like
EFI loader support, for example). I am on holiday ATM with limited
access to my home PC (slow internet), however, one can easily recreate
the issue on the current master by just adding CONFIG_OF_CONTROL=y to
N900 defconfig. Build will fail (no DTS), but no_dts binary built is
well above 350kB vs ~240kB without .
In regards to SPL - there is no way to sign SPL with the keys used by
Nokia to sign NOLO(the proprietary second stage loader), we simply don't
have them. Without that, we can't replace NOLO.
Ivo
- Simon
Not mentioning that implementing this means to implement all N900 code
in U-Boot from scratch. And the last thing is testing...
For me this idea looks like total perfectionism in corporate world when
some software architect invent a new super-duper-über solution for
everything which in reality is not possible to implement.
PS: In past few people investigated topic on cracking RSA signature on
Omap3 and nobody was able to find any "security issue" in it...
- A patch to rework things so that USB gadget support more cleanly
removes from the code paths non-gadget code, so there's no #if's being
added here. Or some similar clean-up.
--
Tom
