[oe-commits] [openembedded-core] 03/12: machine/qemu*: fix kernel finish crng init more and more slowly

Mon Nov 12 13:29:37 UTC 2018

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rpurdie pushed a commit to branch master-next
in repository openembedded-core.

commit 4333ab5c7ee6e80b6157abc70e56afa58d11ef50
Author: Hongxu Jia <hongxu.jia at windriver.com>
AuthorDate: Mon Oct 29 22:22:49 2018 -0400

    machine/qemu*: fix kernel finish crng init more and more slowly
    
    Just adding `-device virtio-rng-pci' to the QEMU invocation will
    add the device with a default host backend. As of QEMU 1.3+,
    the default backend is to use the host's /dev/random as a
    source of entropy. [1]
    
    When the entropy pool is empty, reads from /dev/random will
    block until additional environmental noise is gathered. [2]
    
    For Yocto, if call runqemu frequently, it will consume lots
    of host's /dev/random, and kernel finish crng init in guest get
    more and more slowly.
    
    Here are 4 times runqemu boot test:
    
    [    3.464432] random: crng init done
    [   20.874030] random: crng init done
    [   23.583589] random: crng init done
    [   23.858945] random: crng init done
    
    Modify entropy source to /dev/urandom device on the host which
    returns random bytes using a pseudorandom number generator seeded
    from the entropy pool. Reads from this device do not block and
    kernel finish crng init in guest will not delay.
    
    Of course, the side effect is obviously, we lost the quality of
    randomness, but the modification is only on runqemu script
    rather than real embedded device, and it benefits oeqa efficiency
    in which many cases call runqemu especially multiple oeqa builds
    on one host.
    
    After apply the fix:
    
    [    3.364670] random: crng init done
    [    4.619061] random: crng init done
    [    3.403897] random: crng init done
    [    3.450717] random: crng init done
    
    [1] https://wiki.qemu.org/Features/VirtIORNG
    [2] http://man7.org/linux/man-pages/man4/random.4.html
    
    Signed-off-by: Hongxu Jia <hongxu.jia at windriver.com>
    Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
---
 meta/conf/machine/include/qemuboot-mips.inc | 3 ++-
 meta/conf/machine/include/qemuboot-x86.inc  | 3 ++-
 meta/conf/machine/qemuarm.conf              | 3 ++-
 meta/conf/machine/qemuarm64.conf            | 4 +++-
 meta/conf/machine/qemuppc.conf              | 3 ++-
 5 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/meta/conf/machine/include/qemuboot-mips.inc b/meta/conf/machine/include/qemuboot-mips.inc
index 7d9fa52..75bb988 100644
--- a/meta/conf/machine/include/qemuboot-mips.inc
+++ b/meta/conf/machine/include/qemuboot-mips.inc
@@ -3,6 +3,7 @@ IMAGE_CLASSES += "qemuboot"
 QB_MEM = "-m 256"
 QB_MACHINE = "-machine malta"
 QB_KERNEL_CMDLINE_APPEND = "console=ttyS0 console=tty"
+QB_OPT_APPEND = "-vga cirrus -show-cursor -usb -device usb-tablet"
 # Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
-QB_OPT_APPEND = "-vga cirrus -show-cursor -usb -device usb-tablet -device virtio-rng-pci"
+QB_OPT_APPEND += "-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0"
 QB_SYSTEM_NAME = "qemu-system-${TUNE_ARCH}"
diff --git a/meta/conf/machine/include/qemuboot-x86.inc b/meta/conf/machine/include/qemuboot-x86.inc
index 1456bf7..5fdbe4d 100644
--- a/meta/conf/machine/include/qemuboot-x86.inc
+++ b/meta/conf/machine/include/qemuboot-x86.inc
@@ -11,7 +11,8 @@ QB_CPU_KVM_x86-64 = "-cpu core2duo"
 QB_AUDIO_DRV = "alsa"
 QB_AUDIO_OPT = "-soundhw ac97,es1370"
 QB_KERNEL_CMDLINE_APPEND = "vga=0 uvesafb.mode_option=${UVESA_MODE} oprofile.timer=1 uvesafb.task_timeout=-1"
+QB_OPT_APPEND = "-vga vmware -show-cursor -usb -device usb-tablet"
 # Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
-QB_OPT_APPEND = "-vga vmware -show-cursor -usb -device usb-tablet -device virtio-rng-pci"
+QB_OPT_APPEND += "-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0"
 
 UVESA_MODE ?= "640x480-32"
diff --git a/meta/conf/machine/qemuarm.conf b/meta/conf/machine/qemuarm.conf
index d2f2c85..a544312 100644
--- a/meta/conf/machine/qemuarm.conf
+++ b/meta/conf/machine/qemuarm.conf
@@ -14,7 +14,8 @@ SERIAL_CONSOLES ?= "115200;ttyAMA0 115200;ttyAMA1"
 QB_SYSTEM_NAME = "qemu-system-arm"
 QB_MACHINE = "-machine versatilepb"
 QB_KERNEL_CMDLINE_APPEND = "console=ttyAMA0,115200 console=tty"
+QB_OPT_APPEND = "-show-cursor -usb -device usb-tablet"
 # Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
-QB_OPT_APPEND = "-show-cursor -usb -device usb-tablet -device virtio-rng-pci"
+QB_OPT_APPEND += "-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0"
 PREFERRED_VERSION_linux-yocto ??= "4.18%"
 QB_DTB = "${@oe.utils.version_less_or_equal('PREFERRED_VERSION_linux-yocto', '4.7', '', 'zImage-versatile-pb.dtb', d)}"
diff --git a/meta/conf/machine/qemuarm64.conf b/meta/conf/machine/qemuarm64.conf
index 242889a..34fcd2a 100644
--- a/meta/conf/machine/qemuarm64.conf
+++ b/meta/conf/machine/qemuarm64.conf
@@ -16,7 +16,9 @@ QB_MACHINE = "-machine virt"
 QB_CPU = "-cpu cortex-a57"
 QB_KERNEL_CMDLINE_APPEND = "console=ttyAMA0,38400"
 # Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
-QB_OPT_APPEND = "-show-cursor -device virtio-rng-pci -monitor null"
+QB_OPT_APPEND = "-show-cursor -monitor null"
+# Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
+QB_OPT_APPEND += "-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0"
 QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no"
 QB_NETWORK_DEVICE = "-device virtio-net-device,netdev=net0,mac=@MAC@"
 QB_ROOTFS_OPT = "-drive id=disk0,file=@ROOTFS@,if=none,format=raw -device virtio-blk-device,drive=disk0"
diff --git a/meta/conf/machine/qemuppc.conf b/meta/conf/machine/qemuppc.conf
index 537b2f6..743d261 100644
--- a/meta/conf/machine/qemuppc.conf
+++ b/meta/conf/machine/qemuppc.conf
@@ -16,6 +16,7 @@ QB_SYSTEM_NAME = "qemu-system-ppc"
 QB_MACHINE = "-machine mac99"
 QB_CPU = "-cpu G4"
 QB_KERNEL_CMDLINE_APPEND = "console=tty console=ttyS0"
+QB_OPT_APPEND = "-show-cursor -usb -device usb-tablet"
 # Add the 'virtio-rng-pci' device otherwise the guest may run out of entropy
-QB_OPT_APPEND = "-show-cursor -usb -device usb-tablet -device virtio-rng-pci"
+QB_OPT_APPEND += "-object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0"
 QB_TAP_OPT = "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no"

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