commit 62033c3746951540dd9fc9e96920325cc6f13764
author Jiyong Park <jiyong@google.com> Thu Jul 07 16:07:13 2022 +0900
committer Jiyong Park <jiyong@google.com> Fri Jul 08 11:46:49 2022 +0900
tree b6b1e58c147e3e4cdb1ed4f195b8e52683a9f0bd
parent 8edb55379f3d7b4648dc6d2c6ed91e4d283cc7a3

Reserve memory for the crash-gathering kernel

Microdroid kernel now boots with the `crashkernel=<size>M` cmdline
option to reserve some memory space for use by the crashdumping kernel.

Currently, we reserve this statically, i.e. regardless of whether
ramdump is enabled or not. This can't be moved to the bootconfig because
the memory reservation happens 'before' bootconfig is read. If we move
this config to bootconfig, the kernel doesn't reserve any space.

Ideally, this shall be done conditionally. The bootloader (u-boot) will
append the option at runtime when the ramdump is enabled.

Bug: 237381762
Test: cat /proc/iomem in Microdroid shows ...
80000000-92bfffff : System RAM
  80210000-827bffff : Kernel code
  827c0000-8291ffff : reserved
  82920000-82beffff : Kernel data
  87fff000-87ffffff : reserved
  8f000000-903fffff : Crash kernel
  90400000-913fffff : reserved

Test: /system/bin/kexec /system/etc/microdroid_crashdump_kernel
/system/etc/microdroid_crashdump_initrd.img "1 rdinit=/bin/crashdump
nr_cpus=1 reset_devices console=hvc0 earlycon=uart8250,mmio,0x3f8" in
Microdroid works.

Change-Id: I7d8de4bbaf3c7bb40b15b478ed224acd7f543f29