Sorry, forgive me. I don't know how to reply the email like you. My linux kernel version is 3.11, and I do not touch the kvm makefile. Now let me show you in detail. First I put the files of my module in " /arch/x86/logger ", "logger" is the directory I create. The Makefile in " /arch/x86/kvm/" I think is the Makefile of kvm. It is like this:
ccflags-y += -Ivirt/kvm -Iarch/x86/kvm CFLAGS_x86.o := -I. CFLAGS_svm.o := -I. CFLAGS_vmx.o := -I. KVM := ../../../virt/kvm kvm-y += $(KVM)/kvm_main.o $(KVM)/ioapic.o \ $(KVM)/coalesced_mmio.o $(KVM)/irq_comm.o \ $(KVM)/eventfd.o $(KVM)/irqchip.o kvm-$(CONFIG_KVM_DEVICE_ASSIGNMENT) += $(KVM)/assigned-dev.o $(KVM)/iommu.o kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o kvm-y += x86.o mmu.o emulate.o i8259.o irq.o lapic.o \ i8254.o cpuid.o pmu.o kvm-intel-y += vmx.o kvm-amd-y += svm.o obj-$(CONFIG_KVM) += kvm.o obj-$(CONFIG_KVM_INTEL) += kvm-intel.o obj-$(CONFIG_KVM_AMD) += kvm-amd.o And the Makefile of my module in "/arch/x86/logger" is like this: ifneq ($(KERNELRELEASE),) obj-m := logger.o logger-objs := logger_main.o else KERNELDIR ?= /lib/modules/$(shell uname -r)/build PWD := $(shell pwd) modules: $(MAKE) -C $(KERNELDIR) M=$(PWD) modules endif clean: rm -rf *.o *.ko *.mod.c So I compile my module first by running "make", then insmod it. I don't install it because I don't know if it is necessary. Then I go to the root of my linux code, and run a shell containing "make modules". Then it will show that : make -j 16 modules make[1]: Nothing to be done for `all'. CHK include/generated/uapi/linux/version.h make[1]: Nothing to be done for `relocs'. CHK include/generated/utsrelease.h CALL scripts/checksyscalls.sh CC [M] arch/x86/kvm/x86.o LD [M] arch/x86/kvm/kvm.o LD [M] arch/x86/kvm/kvm-intel.o LD [M] arch/x86/kvm/kvm-amd.o Building modules, stage 2. MODPOST 2832 modules ERROR: "print_record" [arch/x86/kvm/kvm.ko] undefined! make[1]: *** [__modpost] Error 1 make: *** [modules] Error 2 rmmod kvm_intel rmmod kvm cp /home/tanle/study/replay/linux-log/linux-3.11-replay/arch/x86/kvm/kvm.ko /lib/modules/3.11.0+/kernel/arch/x86/kvm/kvm.ko cp /home/tanle/study/replay/linux-log/linux-3.11-replay/arch/x86/kvm/kvm-intel.ko /lib/modules/3.11.0+/kernel/arch/x86/kvm/kvm-intel.ko modprobe kvm modprobe kvm_intel Notice that I add two sentences to the /arch/x86/kvm/x86.c: extern void print_record(char *format); //This functino is defined in my module, this sentence is global print_record(NULL); //Call this function in the vcpu_enter_guest() function So I don't know how to deal with this. I have poor knowledge about makefile and KBuild. Thanks for helping me again! 2014/1/14 Chetan Nanda <[email protected]> > > > > On Tue, Jan 14, 2014 at 12:38 PM, Le Tan <[email protected]> wrote: > >> Thanks very much! I will try that later. What you mentioned is another >> amazing sight. But I am confused that why it can't work if I export a >> function from my module and call it in the kvm? Do I have to modify the >> makefile of kvm? How? I have referenced to the doc of KBuild. It said that : >> Sometimes, an external module uses exported symbols from >> another external module. kbuild needs to have full knowledge of >> all symbols to avoid spliitting out warnings about undefined >> symbols. Three solutions exist for this situation. >> >> NOTE: The method with a top-level kbuild file is recommended >> but may be impractical in certain situations. >> >> Use a top-level kbuild file >> If you have two modules, foo.ko and bar.ko, where >> foo.ko needs symbols from bar.ko, you can use a >> common top-level kbuild file so both modules are >> compiled in the same build. Consider the following >> directory layout: >> >> ./foo/ <= contains foo.ko >> ./bar/ <= contains bar.ko >> >> The top-level kbuild file would then look like: >> >> #./Kbuild (or ./Makefile): >> obj-y := foo/ bar/ >> >> And executing >> >> $ make -C $KDIR M=$PWD >> >> will then do the expected and compile both modules with >> full knowledge of symbols from either module. >> >> Use an extra Module.symvers file >> When an external module is built, a Module.symvers file >> is generated containing all exported symbols which are >> not defined in the kernel. To get access to symbols >> from bar.ko, copy the Module.symvers file from the >> compilation of bar.ko to the directory where foo.ko is >> built. During the module build, kbuild will read the >> Module.symvers file in the directory of the external >> module, and when the build is finished, a new >> Module.symvers file is created containing the sum of >> all symbols defined and not part of the kernel. >> >> Use "make" variable KBUILD_EXTRA_SYMBOLS >> If it is impractical to copy Module.symvers from >> another module, you can assign a space separated list >> of files to KBUILD_EXTRA_SYMBOLS in your build file. >> These files will be loaded by modpost during the >> initialization of its symbol tables. >> >> But I have tried those methods. They don't work. Why? >> Thanks for your help very much! >> > > Please show your kvm module makefile, > > >> >> > >> >> 2014/1/14 Henrique Rodrigues <[email protected]> >> >>> Hi Le, >>> >>> You can do that by exporting a function pointer from the kvm code that >>> is only called if it is not null. Then, when you load your module, you set >>> that exported function pointer (I'm assuming that you want to call your >>> module's function from the kvm code... ). Here is a post on how to do that: >>> >>> >>> http://stackoverflow.com/questions/11463184/how-to-use-exported-symbols-in-the-linux-kernel >>> >>> http://stackoverflow.com/questions/1196944/can-i-replace-a-linux-kernel-function-with-a-module >>> >>> Best, >>> -- >>> Henrique Rodrigues >>> http://www.dcc.ufmg.br/~hsr >>> >>> >>> On Mon, Jan 13, 2014 at 2:47 AM, Le Tan <[email protected]> wrote: >>> >>>> Hello! I am writing a device driver module. I define some functions in >>>> the module, for example print_record(). I am doing something in the kvm, so >>>> I want to call print_record() in the file of kvm module, for example, I may >>>> call print_record() in file /arch/x86/kvm/x86.c to put something into my >>>> device driver module. >>>> Now comes the question. >>>> 1. Where should I put the codes of my device driver module? It's the >>>> first time I write the device driver. >>>> 2. After compiling my module, I encounter an error when I compile the >>>> kvm module. >>>> ERROR: "print_record" [arch/x86/kvm/kvm.ko] undefined! >>>> I use EXPORT_SYMBOL(print_record) in my module file. I use "extern" >>>> to declare print_record() and then call print_record() in file x86.c. >>>> To solve this problem, I have tried to copy the Module.symvers from >>>> my module folder to /arch/x86/kvm/. But it doesn't work. I have also tried >>>> to add *KBUILD_EXTRA_SYMBOLS *to the Makefile of kvm. It doesn't work >>>> either. >>>> I cat /proc/kallsyms and find that the type of symbol >>>> "print_record" is "t" ( local text). What should I do? How to call >>>> functions defined in my own module from kvm? Maybe there is something wrong >>>> in Makefiles? >>>> >>>> Any suggestion is appreciated! >>>> Thanks! >>>> >>>> _______________________________________________ >>>> Kernelnewbies mailing list >>>> [email protected] >>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >>>> >>>> >>> >> >> _______________________________________________ >> Kernelnewbies mailing list >> [email protected] >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> >
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