[Buildroot] [git commit] package/qemu: drop host kernel version check
Arnout Vandecappelle (Essensium/Mind)
arnout at mind.be
Sat Aug 3 22:25:52 UTC 2019
commit: https://git.buildroot.net/buildroot/commit/?id=64ef25d738063416ca2a62e772b7841caaab30d9
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/master
There is no clean way to check if a program will actually run using
host-qemu, making this check too restrictive.
Add a warning in the help text.
Signed-off-by: Adam Duskett <Aduskett at gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout at mind.be>
---
package/qemu/Config.in.host | 6 ++++++
package/qemu/qemu.mk | 22 ----------------------
2 files changed, 6 insertions(+), 22 deletions(-)
diff --git a/package/qemu/Config.in.host b/package/qemu/Config.in.host
index 0287f20514..9eceba5021 100644
--- a/package/qemu/Config.in.host
+++ b/package/qemu/Config.in.host
@@ -64,6 +64,12 @@ config BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE
Enables the build of the user-land emulator, which allows to
run user-space applications.
+ Note that system calls made by the emulated user-land are
+ serviced by the running host kernel. Therefore, if the
+ kernel headers used by your target are more recent than
+ the running host kernel, you may run into invalid system
+ calls, which may yield surprising effects.
+
config BR2_PACKAGE_HOST_QEMU_VDE2
bool "VDE2 support"
help
diff --git a/package/qemu/qemu.mk b/package/qemu/qemu.mk
index 2a148c8b6e..d36ec3e655 100644
--- a/package/qemu/qemu.mk
+++ b/package/qemu/qemu.mk
@@ -241,28 +241,6 @@ ifneq ($(HOST_QEMU_HOST_SYSTEM_TYPE),Linux)
$(error "qemu-user can only be used on Linux hosts")
endif
-# kernel version as major*256 + minor
-HOST_QEMU_HOST_SYSTEM_VERSION = $(shell uname -r | awk -F. '{ print $$1 * 256 + $$2 }')
-HOST_QEMU_TARGET_SYSTEM_VERSION = $(shell echo $(BR2_TOOLCHAIN_HEADERS_AT_LEAST) | awk -F. '{ print $$1 * 256 + $$2 }')
-HOST_QEMU_COMPARE_VERSION = $(shell test $(HOST_QEMU_HOST_SYSTEM_VERSION) -ge $(HOST_QEMU_TARGET_SYSTEM_VERSION) && echo OK)
-
-#
-# The principle of qemu-user is that it emulates the instructions of
-# the target architecture when running the binary, and then when this
-# binary does a system call, it converts this system call into a
-# system call on the host machine. This mechanism makes an assumption:
-# that the target binary will not do system calls that do not exist on
-# the host. This basically requires that the target binary should be
-# built with kernel headers that are older or the same as the kernel
-# version running on the host machine.
-#
-
-ifeq ($(BR_BUILDING),y)
-ifneq ($(HOST_QEMU_COMPARE_VERSION),OK)
-$(error "Refusing to build qemu-user: target Linux version newer than host's.")
-endif
-endif # BR_BUILDING
-
else # BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE
HOST_QEMU_OPTS += --disable-linux-user
endif # BR2_PACKAGE_HOST_QEMU_LINUX_USER_MODE
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