From Fedora Project Wiki
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* Fedora 25 includes the dtb for this model: rk3288-veyron-speedy.dtb
* Fedora 25 includes the dtb for this model: rk3288-veyron-speedy.dtb
* As best I can tell from my research, the boot system on this chrome book is called "Depthcharge".
* As best I can tell from my research, the boot system on this chrome book is called "Depthcharge".
 
* Holding down the power button resets the chromebook after a boot attempt hangs.
If I wrap uImage or vmlinuz-4.. with
 
  vbutil_kernel --pack fedora.blob --keyblock fedora.keyblock --signprivate fedora.vbprivk \
--version 4 --vmlinuz vmlinuz-4.8.6* --config kcmdline --bootloader=dummy.boot --arch arm
 
then Booting in developer mode with Ctrl-U gets a blank screen and hangs - with just zero in part 1 and 2, it says it can't find a kernel.  So the firmware is loading the image. 
 
How does initrd get loaded?  Doesn't uImage already incorporate the itb (compiled from its) and include all the platforms in the dtb-* directory?
 
Holding down the power button resets the chromebook after a boot attempt hangs.


Apparently, it reads the kernel packed by vbutil_kernel --pack, verifies the signature, and transfers control to the kernel.  The bootloader doesn't seem to be used - it seems to be all zero on the factory boot partitions.  I don't know what the fedora kernel is missing - there is no output at all.
Apparently, it reads the kernel packed by vbutil_kernel --pack, verifies the signature, and transfers control to the kernel.  The bootloader doesn't seem to be used - it seems to be all zero on the factory boot partitions.  I don't know what the fedora kernel is missing - there is no output at all.


Examining the ChromeOS kernel reveals a FIT image, so I created rk3288.its:
Examining the ChromeOS kernel reveals a FIT image, so I created rk3288.its:
   /dts-v1/;
   /dts-v1/;
 
 
   / {
   / {
       description = "Fedora 25 kernel-4.8.6-300 for ASUS C201PA Chromebook";
       description = "Fedora 25 kernel-4.8.6-300 for ASUS C201PA Chromebook";
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       };
       };
     };
     };
and compiled (in the distro /boot directory) with:
  mkimage -vf rk3288.its rk3288.itb
I wrapped the FIT image with:
  vbutil_kernel --pack        fedora.blob \
                --keyblock    fedora.keyblock    \
                --signprivate fedora.vbprivk    \
                --config      kcmdline          \
                --vmlinuz    rk3288.itb        \
                --bootloader  dummy.boot        \
                --arch arm --version 1
Where dummy.boot is 4k of zeros to match google kernel.  This is a similar size
to factory ChromeOS kernel image.  Now to see if it gets any farther.  I still
don't see how initrd gets loaded.


== Wrapping uboot as "kernel" ==
== Wrapping uboot as "kernel" ==


This page mentions wrapping uboot as a kernel so that the chrome book will boot like a raspberry pi.  Where does one get uboot to wrap?
This page mentions wrapping uboot as a kernel so that the chrome book will boot like a raspberry pi.  Where does one get uboot to wrap?

Revision as of 23:58, 1 March 2017

ASUS C201PA ARM Chromebook

I have mostly questions and only a few answers.

  • Fedora 25 includes the dtb for this model: rk3288-veyron-speedy.dtb
  • As best I can tell from my research, the boot system on this chrome book is called "Depthcharge".
  • Holding down the power button resets the chromebook after a boot attempt hangs.

Apparently, it reads the kernel packed by vbutil_kernel --pack, verifies the signature, and transfers control to the kernel. The bootloader doesn't seem to be used - it seems to be all zero on the factory boot partitions. I don't know what the fedora kernel is missing - there is no output at all.

Examining the ChromeOS kernel reveals a FIT image, so I created rk3288.its: 

 /dts-v1/;
 
 / {
     description = "Fedora 25 kernel-4.8.6-300 for ASUS C201PA Chromebook";
     #address-cells = <1>;
     images {
         kernel@1{
             description = "vmlinuz-4.8.6";
             data = /incbin/("vmlinuz-4.8.6-300.fc25.armv7hl");
             type = "kernel_noload";
             arch = "arm";
             os = "linux";
             compression = "none";
             load = <0>;
             entry = <0>;
         };
         fdt@1{
             description = "rk3288-veyron-speedy";
             data = /incbin/("dtb-4.8.6-300.fc25.armv7hl/rk3288-veyron-speedy.dtb");
             type = "flat_dt";
             arch = "arm";
             compression = "none";
         };
     };
     configurations {
         default = "conf@1";
         conf@1{
             description = "rk3288-veyron-speedy (ASUS C201PA Chromebook)";
             kernel = "kernel@1";
             fdt = "fdt@1";
         };
     };
   };

and compiled (in the distro /boot directory) with: 

 mkimage -vf rk3288.its rk3288.itb

I wrapped the FIT image with: 

 vbutil_kernel --pack        fedora.blob \
               --keyblock    fedora.keyblock    \
               --signprivate fedora.vbprivk     \
               --config      kcmdline           \
               --vmlinuz     rk3288.itb         \
               --bootloader  dummy.boot         \
               --arch arm --version 1

Where dummy.boot is 4k of zeros to match google kernel. This is a similar size to factory ChromeOS kernel image. Now to see if it gets any farther. I still don't see how initrd gets loaded.

Wrapping uboot as "kernel"

This page mentions wrapping uboot as a kernel so that the chrome book will boot like a raspberry pi. Where does one get uboot to wrap?

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