Re: [PATCH v3 4/8] mach-snapdragon: implement capsule update support

Hi Sumit,

...

+/**

• • qcom_configure_capsule_updates() - Configure the DFU string for capsule updates
• • U-Boot is flashed to the boot partition on Qualcomm boards. In most cases there
• • are two boot partitions, boot_a and boot_b. As we don't currently support doing
• • full A/B updates, we only support updating the currently active boot partition.
• • So we need to find the current slot suffix and the associated boot partition.
• • We do this by looking for the boot partition that has the 'active' flag set
• • in the GPT partition vendor attribute bits.
• */

+void qcom_configure_capsule_updates(void) +{

•   struct blk_desc *desc;
  

•   int ret = 0, partnum = -1, devnum;
  

•   static char dfu_string[32] = { 0 };
  

•   char name[32]; /* GPT partition name */
  

•   char *partname = "boot";
  

•   struct udevice *dev = NULL;
  

•   /*
  

•    * There is currently no good way to check how U-Boot is booting, but we have
  

•    * a few hueristics, like here checking if our DTB has a kaslr-seed specified
  

•    * will tell us if we were chainloaded by another bootloader.
  

•    * FIXME: we should do this check once and use some proper API to expose the data.
  

If U-Boot is built with LINUX_KERNEL_IMAGE_HEADER enabled then we should know that U-Boot is built as a replacement of Linux kernel and hence chainloaded. Isn't that what you need here?

Not necessarily, you can build with LINUX_KERNEL_IMAGE_HEADER and then pack U-Boot into XBL or flash it to hyp and it will still run (the kernel header is specifically written to behave like a nop slide). So we can't rely on this.

-Sumit

Kind regards,