On Tue, Jul 19, 2016 at 8:47 AM, Michal Simek michal.simek@xilinx.com wrote:
On 19.7.2016 08:45, Mario Six wrote:
On Tue, Jul 19, 2016 at 7:46 AM, Michal Simek michal.simek@xilinx.com wrote:
On 18.7.2016 14:05, Mario Six wrote:
In certain circumstances it comes in handy to be able to boot into a second U-Boot. But as of now it is not possible to boot a U-Boot binary that is inside a FIT image, which is problematic for projects that e.g. need to guarantee a unbroken chain of trust from SOC all the way into the OS, since the FIT signing mechanism cannot be used.
This patch adds the capability to load such FIT images.
An example its snippet (utilizing signature verification) might look like the following:
images { kernel@1 { description = "2nd stage U-Boot image"; data = /incbin/("u-boot-dtb.img.gz"); type = "kernel";
Isn't this type weird for u-boot itself?
The rest is good.
Thanks, Michal
It is, but the problem is that adding a new type, like "ubootimage," or something like that, would not be as easy as with the platform-specific image types (like, e.g. "rkimage"), which only appear in mkimage, because we'd have to account for this new type in common/bootm.c (essentially, add a lot of additional "|| images.os.type == IH_TYPE_UBOOT").
I didn't think that it was worth the hassle, and it would have the additional minor problem that it would effectively be a synonym of "kernel," so you could declare a regular kernel as having type "ubootimage," and U-Boot would happily boot it; to prevent that we'd have to do more checks, like, e.g. check the os value against the type and only boot if the combination makes sense or some such.
It would be nicer to have a dedicated type, but I think it's too much effort for such a fringe use case; should it become popular, though, I'll happily add a new type :-)
Is the type property even required for this case?
Thanks, Michal
I just tried to boot one without the type, and apparently it is required:
## Loading kernel from FIT Image at 02000000 ... Using 'config@1' configuration Verifying Hash Integrity ... OK Trying 'kernel@1' kernel subimage Description: 2nd stage U-Boot image Type: Unknown Image Compression: gzip compressed Data Start: 0x020000d4 Data Size: 206485 Bytes = 201.6 KiB Sign algo: sha256,rsa4096:ccdc Sign value: ... Verifying Hash Integrity ... sha256,rsa4096:ccdc+ OK No U-Boot ARM Kernel Image Image ERROR: can't get kernel image!
That makes sense, since common/bootm.c checks the image type in several places.
Best regards,
Mario