On Tue, 2020-10-06 at 18:44 +0900, Hajime Tazaki wrote: > Basic Makefiles for building library of nommu mode. Add a new architecture > specific target for installing the resulting library files and headers. > > To make nommu binaries build, UML introduced an additional option, UMMODE > variable, to switch the output file of build: kernel (default), or > library (nommu). Those modes are not able to be ON at the same time. Here you did that again :) I think you should really be up-front about it and call it "kernel" and "library" mode. Then do the ifdefs on library mode etc. Sure, kernel mode will be CONFIG_MMU=y and library mode will be !CONFIG_MMU instead, but it really makes more sense to call things CONFIG_UMMODE_LIB in most cases, I think? Yes, a lot of stuff *does* depend on CONFIG_MMU, and that still makes sense. It just feels like a lot of stuff you made depend on CONFIG_MMU here (or !CONFIG_MMU) really isn't related too much to that, rather than being related to "library mode". > make defconfig ARCH=um UMMODE=library > make ARCH=um UMMODE=library Why not make it a real Kconfig symbol? I find the ARCH=um tricky enough to remember all the time, so much I usually write a "GNUmakefile" with export ARCH=um include Makefile :-) > +config UMMODE_LIB > + bool "UML mode: library mode" > + default y if "$(UMMODE)" = "library" So wait, you _can_ switch that through Kconfig then, because you made it a visible option (string after "bool"). But it won't work, because then you later in the build system etc. still check UMMODE instead of CONFIG_UMMODE_LIB. Seems like something that ought to be fixed one way or the other - at the very least hide this symbol if setting it manually is invalid. > + help > + This mode switches a mode to build a library of UML (Linux > + Kernel Library/LKL). This switch is exclusive to "kernel mode" > + of UML, which is traditional mode of UML. Not sure if that historically made more sense, but you don't have any UMMODE_KERNEL option or something like that, so the help text seems confusing? > + For more detail about LKL, see > + <file:Documentation/virt/uml/lkl.txt>. > + > config MMU > bool > - default y > + default y if !UMMODE_LIB > > config NO_IOMEM > def_bool y > @@ -45,12 +56,12 @@ config LOCKDEP_SUPPORT > > config STACKTRACE_SUPPORT > bool > - default y > + default y if MMU Same as what I said above - there really shouldn't be any inherent reason why STACKTRACE_SUPPORT depends on CONFIG_MMU, is there? Apart from not having implemented it in UMMODE_LIB, that is, and then you should make this if !UMMODE_LIB? > config GENERIC_CALIBRATE_DELAY > bool > - default y > + default y if MMU Same here. This one _surely_ has no relation to MMU. > +ifeq ($(UMMODE),library) > + SUBARCH := um/nommu > +endif > INSTALL_PATH=$(objtree)/tools/um > +ifeq ($(UMMODE),library) Here a few places using UMMODE which must come from the command line. > linux.o: vmlinux > @echo ' LINK $@' > - $(Q)$(OBJCOPY) -R .eh_frame $< $@ > + $(Q)$(OBJCOPY) -R .eh_frame -L sem_init -L sem_post -L sem_wait -L sem_destroy $< $@ Care to explain? > $(Q)mkdir -p $(objtree)/tools/um/lib > > define archhelp > diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile > index 9b63831a69e1..01605ed439cb 100644 > --- a/arch/um/kernel/Makefile > +++ b/arch/um/kernel/Makefile > @@ -14,17 +14,21 @@ CPPFLAGS_vmlinux.lds := -DSTART=$(LDS_START) \ > $(LDS_EXTRA) > extra-y := vmlinux.lds > > -obj-y = config.o exec.o exitcode.o irq.o ksyms.o mem.o \ > - physmem.o process.o ptrace.o reboot.o sigio.o \ > - signal.o syscall.o sysrq.o time.o tlb.o trap.o \ > - um_arch.o umid.o maccess.o kmsg_dump.o skas/ > +obj-y = config.o exitcode.o irq.o ksyms.o \ > + process.o reboot.o sigio.o \ > + signal.o syscall.o time.o \ > + um_arch.o umid.o maccess.o kmsg_dump.o > + > +ifdef CONFIG_MMU > +obj-y += exec.o mem.o physmem.o ptrace.o sysrq.o tlb.o trap.o skas/ > +endif > > obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o > obj-$(CONFIG_GPROF) += gprof_syms.o > obj-$(CONFIG_GCOV) += gmon_syms.o > obj-$(CONFIG_EARLY_PRINTK) += early_printk.o > obj-$(CONFIG_STACKTRACE) += stacktrace.o > -obj-y += user_syms.o > +obj-$(CONFIG_MMU) += user_syms.o > > USER_OBJS := config.o > > diff --git a/arch/um/nommu/um/Kconfig b/arch/um/nommu/um/Kconfig > new file mode 100644 > index 000000000000..20b3eaccb6f0 > --- /dev/null > +++ b/arch/um/nommu/um/Kconfig > @@ -0,0 +1,37 @@ > +config UML_NOMMU > + def_bool y > + depends on !SMP && !MMU again, using MMU to mean "LKL" (both UML_NOMMU and !MMU places) > + select UACCESS_MEMCPY > + select ARCH_THREAD_STACK_ALLOCATOR > + select ARCH_HAS_SYSCALL_WRAPPER You never use this except for the selects, maybe can go elsewhere? > +config 64BIT > + bool > + default y > + > +config GENERIC_CSUM > + def_bool y > + > +config GENERIC_ATOMIC64 > + bool > + default y if !64BIT > + > +config SECCOMP > + bool > + default n > + > +config GENERIC_HWEIGHT > + def_bool y > + > +config GENERIC_CALIBRATE_DELAY > + bool > + default n > + > +config STACKTRACE_SUPPORT > + bool > + default n You ... were just changing these elsewhere, so one of that isn't needed? > +# XXX: need this to work well with tap13.py What's tap13.py?? johannes
