1. 前言
上一篇文章《虚拟化环境搭建及虚拟机创建》中，我们简单介绍了虚拟化环境的搭建和虚拟机创建过程，本文我们将继续介绍虚拟化环境中重要组件QEMU的修改和安装包编译。
我们使用上一篇文章中安装的CentOS 7 X86_64位版本系统作为编译环境。
2. QEMU修改及安装包编译
2.1源码包下载
CentOS官方会跟随Red Hat官方的节奏发布各个组件的新版本源码（CentOS发布的源码相比于Red Hat发布的源码，其中最主要的改变其实是将源码中的Red Hat替换为CentOS，避免侵权问题），读者可以从http://vault.centos.org上下载，本文以当前最新的qemu-kvm-1.5.3-141.el7_4.4.src.rpm源码包为例进行修改和编译。
2.2源码包直接编译安装包
下载得到源码包之后，使用rpmbuild命令直接就可对其进行编译生成安装包，由于前文我们安装的系统中，并没有rpmbuild工具，这里需要手动先安装：
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[lingyuecloud@lingyuecloud qemu-kvm]$ sudo yum install rpm-build |
然后，使用“--rebuild”参数直接编译QEMU源码包：
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[lingyuecloud@lingyuecloud qemu-kvm]$ rpmbuild --rebuild qemu-kvm-1.5.3-141.el7_4.4.src.rpm Installing qemu-kvm-1.5.3-141.el7_4.4.src.rpm warning: user mockbuild does not exist - using root warning: group mockbuild does not exist - using root …… …… warning: user mockbuild does not exist - using root warning: group mockbuild does not exist - using root error: Failed build dependencies: zlib-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 SDL-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 gnutls-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 cyrus-sasl-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libtool is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libaio-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 pciutils-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 pulseaudio-libs-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libiscsi-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 ncurses-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libattr-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libusbx-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 usbredir-devel >= 0.6 is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 texinfo is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 spice-protocol >= 0.12.2 is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 spice-server-devel >= 0.12.0 is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libseccomp-devel >= 1.0.0 is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 gperftools-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libcurl-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 librados2-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 librbd1-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 glusterfs-api-devel >= 3.6.0 is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 glusterfs-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 systemtap is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 systemtap-sdt-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 nss-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libjpeg-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libpng-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libuuid-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 bluez-libs-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 brlapi-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 check-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libcap-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 pixman-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 rdma-core-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 cpp is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 lzo-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 snappy-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 libssh2-devel is needed by qemu-kvm-10:1.5.3-141.el7.centos.4.x86_64 |
命令输出了很多warning（这里省略了部分）。在编译安装包之前，首先会先安装源码rpm包（也就是解压源码包，通常解压到~/rpmbuild/SOURCES/目录下），这里的warning的意思是说，我们下载的源码包是以mockbuild用户和mockbuild用户组打包的（mock软件、mockbuild用户以及mockbuild组用来在chroot环境下编译rpm包），而本地环境没有mockbuild用户和mockbuild用户组来安装源码包，将会使用root用户和root用户组，这个warning并不影响编译成功与否。为消除上述warning，执行下述命令。
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[lingyuecloud@lingyuecloud qemu-kvm]$ sudo groupadd mockbuild [lingyuecloud@lingyuecloud qemu-kvm]$ sudo useradd -s /sbin/nologin -g mockbuild mockbuild |
接下来我们看后面的error，这些error指出编译QEMU安装包依赖指出的软件，而他们并没有被安装。后面我们还将介绍到，rpmbuild命令之所以知道编译QEMU需要这些软件包，是因为这些依赖软件被写在了spec文件中。需要注意的是，编译QEMU安装包需要的这些依赖包，与运行QEMU需要的依赖包（安装QEMU的时候会自动检查）并不相同，虽然有些软件包既在编译QEMU的时候需要，也在运行QEMU的时候需要。
使用以下命令安装所有依赖包：
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[lingyuecloud@lingyuecloud qemu-kvm]$ sudo yum install zlib-devel SDL-devel gnutls-devel cyrus-sasl-devel libtool libaio-devel pciutils-devel pulseaudio-libs-devel libiscsi-devel ncurses-devel libattr-devel libusbx-devel usbredir-devel texinfo spice-protocol spice-server-devel libseccomp-devel gperftools-devel libcurl-devel librados2-devel librbd1-devel glusterfs-api-devel glusterfs-devel systemtap systemtap-sdt-devel nss-devel libjpeg-devel libpng-devel libuuid-devel bluez-libs-devel brlapi-devel check-devel libcap-devel pixman-devel rdma-core-devel cpp lzo-devel snappy-devel libssh2-devel |
然后再运行rpmbuild命令即可编译成功：
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[lingyuecloud@lingyuecloud qemu-kvm]$ rpmbuild --rebuild qemu-kvm-1.5.3-141.el7_4.4.src.rpm Installing qemu-kvm-1.5.3-141.el7_4.4.src.rpm Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.wu0DxD + umask 022 + cd /home/lingyuecloud/rpmbuild/BUILD + cd /home/lingyuecloud/rpmbuild/BUILD + rm -rf qemu-1.5.3 + /usr/bin/tar -xf - + /usr/bin/bzip2 -dc /home/lingyuecloud/rpmbuild/SOURCES/qemu-1.5.3.tar.bz2 + STATUS=0 + '[' 0 -ne 0 ']' + cd qemu-1.5.3 + /usr/bin/chmod -Rf a+rX,u+w,g-w,o-w . + cp /home/lingyuecloud/rpmbuild/SOURCES/bios-256k.bin pc-bios + tar -xf /home/lingyuecloud/rpmbuild/SOURCES/sample_images.tar + echo 'Patch #1 (0000-libcacard-fix-missing-symbols-in-libcacard.so.patch):' Patch #1 (0000-libcacard-fix-missing-symbols-in-libcacard.so.patch): + /usr/bin/patch -p1 --fuzz=0 + /usr/bin/cat /home/lingyuecloud/rpmbuild/SOURCES/0000-libcacard-fix-missing-symbols-in-libcacard.so.patch patching file libcacard/Makefile …… …… Executing(%build): /bin/sh -e /var/tmp/rpm-tmp.x6IUsO + umask 022 + cd /home/lingyuecloud/rpmbuild/BUILD + cd qemu-1.5.3 + buildarch=x86_64-softmmu + extraldflags=-Wl,--build-id + buildldflags=VL_LDFLAGS=-Wl,--build-id + dobuild --target-list=x86_64-softmmu +./configure --prefix=/usr --libdir=/usr/lib64 --sysconfdir=/etc --interp-prefix=/usr/qemu-%M --audio-drv-list=pa,alsa --with-confsuffix=/qemu-kvm --localstatedir=/var --libexecdir=/usr/libexec --with-pkgversion=qemu-kvm-1.5.3-141.el7.centos.4 --disable-strip --disable-qom-cast-debug '--extra-ldflags=-Wl,--build-id -pie -Wl,-z,relro -Wl,-z,now' '--extra-cflags=-O2 -g -pipe -Wall -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIE -DPIE' --enable-trace-backend=dtrace --enable-werror --disable-xen --disable-virtfs --enable-kvm --enable-libusb --enable-spice --enable-seccomp --disable-fdt --enable-docs --disable-sdl --disable-debug-tcg --disable-sparse --disable-brlapi --disable-bluez --disable-vde --disable-curses --enable-curl --enable-libssh2 --enable-vnc-tls --enable-vnc-sasl --enable-linux-aio --enable-smartcard-nss --enable-lzo --enable-snappy --enable-usb-redir --enable-vnc-png --disable-vnc-jpeg --enable-vnc-ws --enable-uuid --disable-vhost-scsi --disable-guest-agent --disable-live-block-ops --disable-live-block-migration --enable-rbd --enable-glusterfs --enable-tcmalloc --block-drv-rw-whitelist=qcow2,raw,file,host_device,blkdebug,nbd,iscsi,gluster,rbd --block-drv-ro-whitelist=vmdk,vhdx,vpc,ssh,https --iasl=/bin/false --target-list=x86_64-softmmu Install prefix /usr BIOS directory /usr/share/qemu-kvm binary directory /usr/bin library directory /usr/lib64 libexec directory /usr/libexec include directory /usr/include config directory /etc local state directory /var Manual directory /usr/share/man ELF interp prefix /usr/qemu-%M Source path /home/lingyuecloud/rpmbuild/BUILD/qemu-1.5.3 C compiler cc Host C compiler cc Objective-C compiler cc CFLAGS -O2 -D_FORTIFY_SOURCE=2 -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -g QEMU_CFLAGS -Werror -DHAS_LIBSSH2_SFTP_FSYNC -fPIE -DPIE -m64 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -O2 -g -pipe -Wall -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIE -DPIE -Wendif-labels -Wmissing-include-dirs -Wempty-body -Wnested-externs -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration -Wold-style-definition -Wtype-limits -fstack-protector-strong -I/usr/include/p11-kit-1 -I/usr/include/libpng15 -I/usr/include/spice-server -I/usr/include/cacard -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/nss3 -I/usr/include/nspr4 -I/usr/include/spice-1 -I/usr/include/nss3 -I/usr/include/nspr4 -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/libusb-1.0 -I/usr/include/pixman-1 LDFLAGS -Wl,--warn-common -Wl,-z,relro -Wl,-z,now -pie -m64 -g -Wl,--build-id -pie -Wl,-z,relro -Wl,-z,now make make install install python python smbd /usr/sbin/smbd host CPU x86_64 host big endian no target list x86_64-softmmu …… …… Processing files: qemu-kvm-debuginfo-1.5.3-141.el7.centos.4.x86_64 Provides: qemu-kvm-debuginfo = 10:1.5.3-141.el7.centos.4 qemu-kvm-debuginfo(x86-64) = 10:1.5.3-141.el7.centos.4 Requires(rpmlib): rpmlib(FileDigests) <= 4.6.0-1 rpmlib(PayloadFilesHavePrefix) <= 4.0-1 rpmlib(CompressedFileNames) <= 3.0.4-1 Checking for unpackaged file(s): /usr/lib/rpm/check-files /home/lingyuecloud/rpmbuild/BUILDROOT/qemu-kvm-1.5.3-141.el7_4.4.x86_64 Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-1.5.3-141.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-img-1.5.3-141.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-common-1.5.3-141.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-tools-1.5.3-141.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-debuginfo-1.5.3-141.el7.centos.4.x86_64.rpm Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.5aHHpJ + umask 022 + cd /home/lingyuecloud/rpmbuild/BUILD + cd qemu-1.5.3 + /usr/bin/rm -rf /home/lingyuecloud/rpmbuild/BUILDROOT/qemu-kvm-1.5.3-141.el7_4.4.x86_64 + exit 0 Executing(--clean): /bin/sh -e /var/tmp/rpm-tmp.qutzZw + umask 022 + cd /home/lingyuecloud/rpmbuild/BUILD + rm -rf qemu-1.5.3 + exit 0 |
整个编译过程中输出的日志非常长，我们这里只截取了部分。从输出日志的开始可以看到，编译过程中首先是打Patch（后面我们会将源码rpm包解开，可以看到里面有很多Patch），然后spec文件会根据当前环境选择configure参数进行configure，然后执行编译。最后，“Wrote:/home/lingyuecloud/rpmbuild/RPMS/x86_64/******.rpm”是编译完成后输出的rpm安装包，可使用“rpm -ivh ******.rpm”命令来安装即可。
使用源码包直接编译是最简单的编译方法，但是其缺点是我们没有对源码或者编译过程进行修改，接下来我们将介绍如何修改源码并编译。
2.3源码包解压编译安装包
2.3.1 源码包文件分析
首先使用命令对源码包进行解压，看看其中包含的文件：
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[lingyuecloud@lingyuecloud qemu]$ rpm2cpio qemu-kvm-1.5.3-141.el7_4.4.src.rpm | cpio -di 64177 blocks [lingyuecloud@lingyuecloud qemu]$ ls 0000-libcacard-fix-missing-symbols-in-libcacard.so.patch 80-kvm.rules 99-qemu-guest-agent.rules bios-256k.bin block-add-block-driver-read-only-whitelist.patch bridge.conf change-path-from-qemu-to-qemu-kvm.patch disable-hpet-device.patch …… …… e1000-Keep-capabilities-list-bit-on-for-older-RHEL-machine-types.patch ksmctl.c ksm.service ksm.sysconfig ksmtuned ksmtuned.conf ksmtuned.service kvm-ac97-register-reset-via-qom.patch …… …… qemu-1.5.3.tar.bz2 qemu.binfmt qemu-ga.sysconfig qemu-guest-agent.service qemu-kvm-1.5.3-141.el7_4.4.src.rpm qemu-kvm-Fix-migration-from-older-version-due-to-i8254-changes.patch qemu-kvm.spec qxl-set-revision-to-1-for-rhel6-0-0.patch README.rhel6-gpxe-source rename-man-page-to-qemu-kvm.patch rhel6-e1000.rom rhel6-ne2k_pci.rom rhel6-pcnet.rom rhel6-rtl8139.rom rhel6-virtio.rom sample_images.tar target-i386-set-level-4-on-conroe-penryn-nehalem.patch target-i386-update-model-values-on-conroe-penryn-nehalem-cpu-models.patch use-kvm-by-default.patch vga-Default-vram_size_mb-to-16-like-prior-versions-of-RHEL.patch vmdk-Allow-reading-variable-size-descriptor-files.patch vmdk-refuse-to-open-higher-version-than-supported.patch …… |
其中包含了几部分，主要包括：patch文件（1746个，此处省略了部分）、QEMU官方release的源码包(qemu-1.5.3.tar.bz2)、编译QEMU的时候用到的其他源码及资源文件，以及控制编译的spec文件(qemu-kvm.spec)。
spec文件内容非常多，关于spec文件的语法等知识，有兴趣的读者可以参阅Fedora官方文档Creating RPM Packages with Fedora。这里，我们简单看下spec文件中的部分内容：
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[lingyuecloud@lingyuecloud qemu]$ cat qemu-kvm.spec …… %define pkgname qemu-kvm %define rhel_suffix -rhel %define rhev_suffix -rhev …… Summary: QEMU is a machine emulator and virtualizer Name: %{pkgname}%{?pkgsuffix} Version: 1.5.3 Release: 141%{?dist}.4 # Epoch because we pushed a qemu-1.0 package. AIUI this can't ever be dropped Epoch: 10 License: GPLv2+ and LGPLv2+ and BSD Group: Development/Tools URL: http://www.qemu.org/ ExclusiveArch: x86_64 %{power64} aarch64 s390x Requires: seabios-bin >= 1.7.2.2-5 Requires: sgabios-bin Requires: seavgabios-bin Requires: ipxe-roms-qemu …… …… Source0: http://wiki.qemu-project.org/download/qemu-%{version}.tar.bz2 Source1: qemu.binfmt …… BuildRequires: zlib-devel BuildRequires: SDL-devel BuildRequires: which BuildRequires: gnutls-devel BuildRequires: cyrus-sasl-devel BuildRequires: libtool BuildRequires: libaio-devel BuildRequires: rsync BuildRequires: python BuildRequires: pciutils-devel BuildRequires: pulseaudio-libs-devel BuildRequires: libiscsi-devel BuildRequires: ncurses-devel BuildRequires: libattr-devel BuildRequires: libusbx-devel …… …… |
其中，“Version和Release”控制了最终输出rpm包的版本号，其中的dist变量在我们环境中值为.el7.centos。“Source0”值指定了源码包的下载路径，本地编译的时候，不会从这个url去下载源码，只会根据这个url末尾的文件名从本地寻找源码包（本例中为qemu-1.5.3.tar.bz2），若用户希望将修改后的源码打包为.tar.gz格式或其他格式，修改此处url中的后缀名即可。“Requires”字段指定了编译生成的QEMU安装包在安装时所需要的依赖软件，“BuildRequires”指定了在编译时依赖的软件包。
2.3.2 编译安装包
要编译rpm包，只需将前文解压出来的所有文件复制到编译目录“~/rpmbuild/SOURCES/”（执行安装命令“rpm -ivh qemu-kvm-1.5.3-141.el7_4.4.src.rpm”也会将所需文件解压到编译目录），然后执行编译命令即可编译成功。
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[lingyuecloud@lingyuecloud SOURCES]$ rpmbuild -bb qemu-kvm.spec |
接下来，我们修改qemu-1.5.3.tar.bz2中的源码。需要特别注意的是，因为spec文件中有打Patch的过程，对qemu-1.5.3.tar.bz2源码的修改很可能导致后续的打Patch过程失败，所以，实际进行项目开发时，通常是首先将Patch打完，之后注释掉spec文件中打Patch的过程，最后在此基础上进行开发。
由于Patch较多，本文演示的改动较小，因此暂时先不打Patch，直接修改源码进行编译。
首先解压qemu-1.5.3.tar.bz2：
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[lingyuecloud@lingyuecloud SOURCES]$ tar -jxf qemu-1.5.3.tar.bz2 [lingyuecloud@lingyuecloud SOURCES]$ cd qemu-1.5.3 |
编辑vl.c文件，在QEMU的main_loop函数中增加一行日志：
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…… …… static void main_loop(void) { bool nonblocking; int last_io = 0; #ifdef CONFIG_PROFILER int64_t ti; #endif fprintf(stderr, "Hello, welcome to lingyuecloud.com "); do { nonblocking = !kvm_enabled() && !xen_enabled() && last_io > 0; #ifdef CONFIG_PROFILER ti = profile_getclock(); #endif last_io = main_loop_wait(nonblocking); #ifdef CONFIG_PROFILER dev_time += profile_getclock() - ti; #endif } while (!main_loop_should_exit()); } …… …… |
然后修改spec文件，更新release版本号以示区别：
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…… Summary: QEMU is a machine emulator and virtualizer Name: %{pkgname}%{?pkgsuffix} Version: 1.5.3 Release: 141.20171220.lingyuecloud%{?dist}.4 # Epoch because we pushed a qemu-1.0 package. AIUI this can't ever be dropped Epoch: 10 License: GPLv2+ and LGPLv2+ and BSD …… …… |
将修改后的源码打包并编译：
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[lingyuecloud@lingyuecloud SOURCES]$ mv qemu-1.5.3.tar.bz2 qemu-1.5.3.tar.gz.bak [lingyuecloud@lingyuecloud SOURCES]$ tar -jcf qemu-1.5.3.tar.bz2 qemu-1.5.3 [lingyuecloud@lingyuecloud SOURCES]$ rpmbuild -bb qemu-kvm.spec …… …… Processing files: qemu-kvm-debuginfo-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64 Provides: qemu-kvm-debuginfo = 10:1.5.3-141.20171220.lingyuecloud.el7.centos.4 qemu-kvm-debuginfo(x86-64) = 10:1.5.3-141.20171220.lingyuecloud.el7.centos.4 Requires(rpmlib): rpmlib(FileDigests) <= 4.6.0-1 rpmlib(PayloadFilesHavePrefix) <= 4.0-1 rpmlib(CompressedFileNames) <= 3.0.4-1 Checking for unpackaged file(s): /usr/lib/rpm/check-files /home/lingyuecloud/rpmbuild/BUILDROOT/qemu-kvm-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64 Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-img-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-common-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-tools-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm Wrote: /home/lingyuecloud/rpmbuild/RPMS/x86_64/qemu-kvm-debuginfo-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.0ckghW + umask 022 + cd /home/lingyuecloud/rpmbuild/BUILD + cd qemu-1.5.3 + /usr/bin/rm -rf /home/lingyuecloud/rpmbuild/BUILDROOT/qemu-kvm-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64 + exit 0 |
可以看到，输出的rpm包版本号已经更新为我们设置的版本号。
接下来，我们更新安装编译好的rpm包，以检查我们的源码修改是否生效：
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[lingyuecloud@lingyuecloud SOURCES]$ cd /home/lingyuecloud/rpmbuild/RPMS/x86_64/ [lingyuecloud@lingyuecloud x86_64]$ sudo rpm -Uvh qemu-kvm-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm qemu-img-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm qemu-kvm-common-1.5.3-141.20171220.lingyuecloud.el7.centos.4.x86_64.rpm [sudo] password for lingyuecloud: Preparing... ################################# [100%] Updating / installing... 1:qemu-kvm-common-10:1.5.3-141.2017################################# [ 17%] 2:qemu-img-10:1.5.3-141.20171220.li################################# [ 33%] 3:qemu-kvm-10:1.5.3-141.20171220.li################################# [ 50%] Cleaning up / removing... 4:qemu-kvm-10:1.5.3-141.el7 ################################# [ 67%] 5:qemu-img-10:1.5.3-141.el7 ################################# [ 83%] 6:qemu-kvm-common-10:1.5.3-141.el7 ################################# [100%] |
然后，按照《虚拟化环境搭建及虚拟机创建》文章所述，使用libvirt启动虚拟机，查看虚拟机日志（在目录“~/.cache/libvirt/qemu/log/”下面，文件名为虚拟机名），即可看到我们加入的日志，如图所示：
图1 虚拟机的QEMU日志
2.4 Configure & Make
除了使用spec文件来编译完整的安装包之外，还可以在源码目录中直接使用configure和make命令进行编译。这种方式的好处是编译过一次之后，只要没有清除编译结果（执行“make clean”命令），下次编译将只会编译修改了源码的部分文件，大大节省了时间。当然，该方式也存在缺点：首先是编译过程依赖的软件包不清晰，如果遇到依赖的软件不存在，出错提示信息也并不直观；其次，使用rpmbuild方式编译安装包时，可以在spec文件中加入测试过程，对编译完成的文件进行一些测试，确保生成的安装包功能正常，而采用Configure & Make方式编译，测试过程需要手动执行；再次，编译生成的文件并没有很好的组织起来，不便于安装到其他环境运行。Configure & Make编译方式通常在开发过程中使用，软件发布时一般不会使用该编译方式。
在前文解压qemu-1.5.3源码目录中，执行./configure（configure后面可加参数，如果没有加参数，configure过程将会自动进行。读者可参考前文rpmbuild日志中的configure参数，或者执行“./configure --help”命令查看各个参数的含义），然后执行make命令即可进行编译。由于前文已经将编译需要的依赖软件安装完成，此处的编译将会很顺利的完成，读者可自行尝试。
3. 总结
本文简要介绍了虚拟化组件QEMU的安装包编译过程，简单修改了QEMU源码，并验证了修改的有效性。由于篇幅所限，控制rpm编译过程的spec文件，以及QEMU的源码分析等，都并没有深入展开叙述，后续的文章中，我们将陆续介绍，敬请期待。