trying to switch boards to use crosvm from source:
  https://chromium-review.googlesource.com/733606

fails:
  https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/pre_cq/builds/63443/steps/BuildPackages/logs/stdio
 >>> Emerging (1 of 1) chromeos-base/crosvm-0.0.1-r9::chromiumos for /build/betty/
  * byteorder-1.1.0.crate SHA256 SHA512 WHIRLPOOL size ;-) ...            [ ok ]
  * libc-0.2.29.crate SHA256 SHA512 WHIRLPOOL size ;-) ...                [ ok ]
  * gcc-0.3.54.crate SHA256 SHA512 WHIRLPOOL size ;-) ...                 [ ok ]
  * Running stacked hooks for pre_pkg_setup
  *    sysroot_build_bin_dir ...
  [ ok ]
  * Running stacked hooks for post_pkg_setup
  *    python_eclass_hack ...
  [ ok ]
  * Running stacked hooks for pre_src_unpack
  *    python_multilib_setup ...
  [ ok ]
 >>> Unpacking source...
  * Loading byteorder-1.1.0.crate into Cargo registry ...
  [ ok ]
  * Loading libc-0.2.29.crate into Cargo registry ...
  [ ok ]
  * Loading gcc-0.3.54.crate into Cargo registry ...
  [ ok ]
  * Using local source dir(s): /mnt/host/source/src/platform/../platform/crosvm
  * path: /mnt/host/source/src/platform/../platform/crosvm
  * destdir: /build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/work/crosvm-0.0.1
 >>> Source unpacked in /build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/work
  * Running stacked hooks for post_src_unpack
  *    asan_init ...
  [ ok ]
 >>> Preparing source in /mnt/host/source/src/platform/crosvm ...
 >>> Source prepared.
 >>> Configuring source in /mnt/host/source/src/platform/crosvm ...
 >>> Source configured.
 >>> Compiling source in /mnt/host/source/src/platform/crosvm ...
  * ACCESS DENIED:  mkdir:        /mnt/host/source/src/platform/crosvm/target
 error: failed to open: /mnt/host/source/src/platform/crosvm/target/release/.cargo-lock
 
 Caused by:
   Permission denied (os error 13)
  * ERROR: chromeos-base/crosvm-0.0.1-r9::chromiumos failed (compile phase):
  *   cargo build failed
  * 
  * Call stack:
  *     ebuild.sh, line   93:  Called src_compile
  *   environment, line 3449:  Called cargo_src_compile
  *   environment, line  704:  Called die
  * The specific snippet of code:
  *       cargo build -v $(usex debug "" --release) || die "cargo build failed"
  * 
  * If you need support, post the output of `emerge --info '=chromeos-base/crosvm-0.0.1-r9::chromiumos'`,
  * the complete build log and the output of `emerge -pqv '=chromeos-base/crosvm-0.0.1-r9::chromiumos'`.
  * The complete build log is located at '/build/betty/tmp/portage/logs/chromeos-base:crosvm-0.0.1-r9:20171024-051846.log'.
  * For convenience, a symlink to the build log is located at '/build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/temp/build.log'.
  * The ebuild environment file is located at '/build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/temp/environment'.
  * Working directory: '/mnt/host/source/src/platform/crosvm'
  * S: '/mnt/host/source/src/platform/../platform/crosvm'
  * --------------------------- ACCESS VIOLATION SUMMARY ---------------------------
  * LOG FILE: "/var/log/sandbox/sandbox-26859.log"
  * 
 VERSION 1.0
 FORMAT: F - Function called
 FORMAT: S - Access Status
 FORMAT: P - Path as passed to function
 FORMAT: A - Absolute Path (not canonical)
 FORMAT: R - Canonical Path
 FORMAT: C - Command Line
 
 F: mkdir
 S: deny
 P: /mnt/host/source/src/platform/crosvm/target
 A: /mnt/host/source/src/platform/crosvm/target
 R: /mnt/host/source/src/platform/crosvm/target
 C: cargo build -v --release 
  * --------------------------------------------------------------------------------
 >>> Failed to emerge chromeos-base/crosvm-0.0.1-r9 for /build/betty/, Log file:
 >>>  '/build/betty/tmp/portage/logs/chromeos-base:crosvm-0.0.1-r9:20171024-051846.log'
 
  * Messages for package chromeos-base/crosvm-0.0.1-r9 merged to /build/betty/:
 
  * ERROR: chromeos-base/crosvm-0.0.1-r9::chromiumos failed (compile phase):
  *   cargo build failed
  * 
  * Call stack:
  *     ebuild.sh, line   93:  Called src_compile
  *   environment, line 3449:  Called cargo_src_compile
  *   environment, line  704:  Called die
  * The specific snippet of code:
  *       cargo build -v $(usex debug "" --release) || die "cargo build failed"
  * 
  * If you need support, post the output of `emerge --info '=chromeos-base/crosvm-0.0.1-r9::chromiumos'`,
  * the complete build log and the output of `emerge -pqv '=chromeos-base/crosvm-0.0.1-r9::chromiumos'`.
  * The complete build log is located at '/build/betty/tmp/portage/logs/chromeos-base:crosvm-0.0.1-r9:20171024-051846.log'.
  * For convenience, a symlink to the build log is located at '/build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/temp/build.log'.
  * The ebuild environment file is located at '/build/betty/tmp/portage/chromeos-base/crosvm-0.0.1-r9/temp/environment'.
  * Working directory: '/mnt/host/source/src/platform/crosvm'
  * S: '/mnt/host/source/src/platform/../platform/crosvm'
=== Complete: job crosvm-0.0.1-r9 (0m2.4s) ===