15 Dec
2020
15 Dec
'20
4:35 p.m.
On Tue, 15 Dec 2020 at 18:25, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 15.12.20 12:10, Sughosh Ganu wrote:
On Wed, 9 Dec 2020 at 03:24, Heinrich Schuchardt <xypron.glpk@gmx.de mailto:xypron.glpk@gmx.de> wrote:
On 12/8/20 10:19 AM, Sughosh Ganu wrote: > > On Tue, 8 Dec 2020 at 14:32, Heinrich Schuchardt <xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> > <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>>> wrote: > > On 08.12.20 06:28, Sughosh Ganu wrote: > > > > On Mon, 7 Dec 2020 at 23:28, Heinrich Schuchardt > <xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>> > > <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>>>> wrote: > > > > On 07.12.20 13:50, Heinrich Schuchardt wrote: > > > On 07.12.20 06:15, Sughosh Ganu wrote: > > >> hello Heinrich, > > >> > > >> On Sat, 5 Dec 2020 at 15:01, Heinrich Schuchardt > > <xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>> > <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>>> > > >> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>> > <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de> <mailto:xypron.glpk@gmx.de <mailto:xypron.glpk@gmx.de>>>>> wrote: > > >> > > >> On 11/26/20 7:40 PM, Sughosh Ganu wrote: > > >> > The Qemu platform emulator generates a devicetree
> blob and > > places it > > >> > at the start of the dram, which is then used by > u-boot. Use > > this dtb > > >> > only if CONFIG_OF_BOARD is defined. This allows using a > > different > > >> > device tree, using the CONFIG_OF_SEPARATEoption.
> This dtb > > is attached > > >> > to the u-boot binary as a u-boot-fdt.bin file > > >> > > >> Dear Sughosh, > > >> > > >> thank your for this series which will allow us to better > > demonstrate and > > >> test capsule updates. > > >> > > >> I am not sure if the approach that you take at > device-trees > > here is the > > >> right one. > > >> > > >> On QEMU the device-tree is generated on the fly by the > QEMU > > binary > > >> depending on which devices the user hasspecified.
> > >> > > >> Your idea is to replace this device-tree completely to be > > able to add > > >> extra elements (the EFI signature list, see patch > 2/14). Thus a > > >> device-tree might be loaded that does not matchthe
> user selected > > >> devices. > > >> > > >> An alternative approach would be to apply all > additions to the > > >> device-tree as an FDT overlay (or fixup). This would allow > > the dynamic > > >> parts of the QEMU device-tree still to be passed through. > > >> > > >> > > >> I will take a look at storing the public key as partof
> the fdt > > overlay, > > >> with a runtime fixup. Although, I think the issue that you are > > pointing > > >> to would be specific to Qemu and not other platforms. But I do > > see the > > >> merit in having the public-key certificate stored as part > of an > > overlay. > > >> If I hit any issues while implementing this, I willget
> back to > > you. Thanks. > > >> > > >> -sughosh > > > > > > OpenSBI can supply a device-tree to U-Boot. So this would be an > > > equivalent case. > > > > > > Best regards > > > > > > Heinrich > > > > <sng_>: "I am unable to think of a simple and elegant way to > generate > > the overlay dtb, since this would require creation of a > corresponding > > dts file, compiling it into a dtb and then using this on the > platform." > > > > Jean-Jacques' patch series introduced some of the necessary code: > > > > [PATCH PATCH v6 00/13] Add support for applications of > overlays in SPL > > https://lists.denx.de/pipermail/u-boot/2019-October/387653.html <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html> > <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html>> > > > <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html> > <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html <https://lists.denx.de/pipermail/u-boot/2019-October/387653.html>>> > > >https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
<https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
> <https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
<https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
> > > <https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
<https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
<https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
<https://patchwork.ozlabs.org/project/uboot/list/?series=137810&state=%2A...
> > > > CONFIG_OF_OVERLAY_LIST is used to specify the overlays to be > compiled. > > You will have to remove the CONFIG_SPL_LOAD_FIT_APPLY_OVERLAY and > > CONFIG_SPL_LOAD_FIT dependency. > > > > > > What i meant was that the process to generate the fdt overlay on the > > host, embed it with the public-key certificate is more cumbersome > than > > the current solution. So, for comparing the embedding the pub-key > cert > > in the fdt overlay, as against the platform dtb > > > > Embedding the certificate in the overlay > > 1) Generate a skeleton overlay dts file > > 2) Convert it to a dtb > > 3) Run it through the mkeficapsule utility to embed thepub-key
> > certificate in the overlay(dtb) > > 4) Store the overlay dtb on some nv storage on theplatform(ESP
> partition?) > > 5) Load the overlay and apply it to the platform's dtb > > 6) Retrieve the certificate from the dtb at the time ofcapsule
> > authentication > > > > Embedding the certificate in the platform's dtb > > 1) Run the platform's dtb through the mkeficapsule utility to embed > > the pub-key certificate > > 2) Boot the platform with the platform's dtb > > 3) Retrieve the certificate from the dtb at the time ofcapsule
> > authentication > > > > You had mentioned OpenSBI passing the dtb to u-boot. Does the OpenSBI > > generate the device tree for the platform on the fly evenfor
> non-qemu > > platforms. If it does not, the dtb that OpenSBI uses can berun
> through > > the mkeficapsule utility to embed the certificate. > > OpenSBI applies fix-ups before passing the device-tree. The prototype > device-tree can either be built into OpenSBI or can be passed from an > earlier firmware stage. > > > So, if qemu if the only platform where the device tree isgenerated on
> the fly, and passed along, based on the comparison that i havestated
> above for the two scenarios(overlay vs platform dtb), I feel that using > the platform's dtb and embedding the certificate is more easier touse
> than using the overlay. > > Even on the qemu platform, I retrieved the dtb from the platform,for
> the given set of devices and interfaces used, and then ran the dtb > through the mkeficapsule utility. > > -sughosh As I understand the whole series is not about productive firmware updates for QEMU but about a demonstration how it could be used and allowing testing. Wouldn't it be the enough for testing to apply an overlay with the public key using the fdt command?Is there a way I can build qemu such that the device-tree that is generated is with the __symbols__ node. Without this node, I am unable to apply the fdt overlay on the base platform devicetree.
According to https://www.kernel.org/doc/Documentation/devicetree/overlay-notes.txt __symbols__ is only needed if you refer to phandles in the overlay. When using paths instead __symbols__ is not required.
I have not tested if this holds true for U-Boot too.
This does work. Thanks. I was referring to the document mentioned in the README.fdt-overlays[1] and that does not have mention of target-path.
-sughosh
[1] - https://git.kernel.org/pub/scm/utils/dtc/dtc.git/tree/Documentation/dt-objec...