From eaf720b285947a6f4e29174d0eba1899de31d8ab Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Mon, 5 Dec 2011 16:16:32 +0200 Subject: [PATCH] kvm tools: Split custom rootfs init into two stages Currently custom rootfs init is built along with the main KVM tools executable and is copied into custom rootfs directories when they are created with 'kvm setup'. The problem there is that if the init code changes, they have to be manually copied to custom rootfs directories. Instead, this patch splits init process into two parts. One part that simply handles mounts, and passes it to stage 2 of the init. Stage 2 really sits along in the code tree, and does all the heavy lifting. This allows us to make init changes in the code tree and have it automatically be updated in custom rootfs guests without having to copy files over manua Signed-off-by: Sasha Levin [ penberg@kernel.org: fix 'make check' breakage in Makefile ] Signed-off-by: Pekka Enberg --- tools/kvm/Makefile | 11 ++++++++--- tools/kvm/builtin-run.c | 27 +++++++++++++++++++++++++++ tools/kvm/guest/init.c | 14 +++----------- tools/kvm/guest/init_stage2.c | 34 ++++++++++++++++++++++++++++++++++ 4 files changed, 72 insertions(+), 14 deletions(-) create mode 100644 tools/kvm/guest/init_stage2.c diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile index bb5f6b0f8127..0325be9c0ed3 100644 --- a/tools/kvm/Makefile +++ b/tools/kvm/Makefile @@ -21,6 +21,7 @@ TAGS := ctags PROGRAM := kvm GUEST_INIT := guest/init +GUEST_INIT_S2 := guest/init_stage2 OBJS += builtin-balloon.o OBJS += builtin-debug.o @@ -179,7 +180,7 @@ WARNINGS += -Wwrite-strings CFLAGS += $(WARNINGS) -all: $(PROGRAM) $(GUEST_INIT) +all: $(PROGRAM) $(GUEST_INIT) $(GUEST_INIT_S2) KVMTOOLS-VERSION-FILE: @$(SHELL_PATH) util/KVMTOOLS-VERSION-GEN $(OUTPUT) @@ -193,6 +194,10 @@ $(GUEST_INIT): guest/init.c $(E) " LINK " $@ $(Q) $(CC) -static guest/init.c -o $@ +$(GUEST_INIT_S2): guest/init_stage2.c + $(E) " LINK " $@ + $(Q) $(CC) -static guest/init_stage2.c -o $@ + $(DEPS): %.d: %.c @@ -255,7 +260,7 @@ bios/bios-rom.h: bios/bios.bin.elf $(E) " NM " $@ $(Q) cd bios && sh gen-offsets.sh > bios-rom.h && cd .. -check: $(PROGRAM) +check: all $(MAKE) -C tests ./$(PROGRAM) run tests/pit/tick.bin ./$(PROGRAM) run -d tests/boot/boot_test.iso -p "init=init" @@ -269,7 +274,7 @@ clean: $(Q) rm -f bios/bios-rom.h $(Q) rm -f tests/boot/boot_test.iso $(Q) rm -rf tests/boot/rootfs/ - $(Q) rm -f $(DEPS) $(OBJS) $(PROGRAM) $(GUEST_INIT) + $(Q) rm -f $(DEPS) $(OBJS) $(PROGRAM) $(GUEST_INIT) $(GUEST_INIT_S2) $(Q) rm -f cscope.* $(Q) rm -f $(KVM_INCLUDE)/common-cmds.h $(Q) rm -f KVMTOOLS-VERSION-FILE diff --git a/tools/kvm/builtin-run.c b/tools/kvm/builtin-run.c index 33de4f6ef927..de3001ed1aef 100644 --- a/tools/kvm/builtin-run.c +++ b/tools/kvm/builtin-run.c @@ -702,6 +702,31 @@ void kvm_run_help(void) usage_with_options(run_usage, options); } +static int kvm_custom_stage2(void) +{ + char tmp[PATH_MAX], dst[PATH_MAX], *src; + const char *rootfs; + int r; + + src = realpath("guest/init_stage2", NULL); + if (src == NULL) + return -ENOMEM; + + if (image_filename[0] == NULL) + rootfs = "default"; + else + rootfs = image_filename[0]; + + snprintf(tmp, PATH_MAX, "%s%s/virt/init_stage2", kvm__get_dir(), rootfs); + remove(tmp); + + snprintf(dst, PATH_MAX, "/host/%s", src); + r = symlink(dst, tmp); + free(src); + + return r; +} + int kvm_cmd_run(int argc, const char **argv, const char *prefix) { static char real_cmdline[2048], default_name[20]; @@ -864,6 +889,8 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix) strcat(real_cmdline, " init=/virt/init"); if (!no_dhcp) strcat(real_cmdline, " ip=dhcp"); + if (kvm_custom_stage2()) + die("Failed linking stage 2 of init."); } } else if (!strstr(real_cmdline, "root=")) { strlcat(real_cmdline, " root=/dev/vda rw ", sizeof(real_cmdline)); diff --git a/tools/kvm/guest/init.c b/tools/kvm/guest/init.c index 8975023cc899..032a261bb36d 100644 --- a/tools/kvm/guest/init.c +++ b/tools/kvm/guest/init.c @@ -1,6 +1,6 @@ /* - * This is a simple init for shared rootfs guests. It brings up critical - * mountpoints and then launches /bin/sh. + * This is a simple init for shared rootfs guests. This part should be limited + * to doing mounts and running stage 2 of the init process. */ #include #include @@ -30,15 +30,7 @@ int main(int argc, char *argv[]) do_mounts(); - /* get session leader */ - setsid(); - - /* set controlling terminal */ - ioctl (0, TIOCSCTTY, 1); - - puts("Starting '/bin/sh'..."); - - run_process("/bin/sh"); + run_process("/virt/init_stage2"); printf("Init failed: %s\n", strerror(errno)); diff --git a/tools/kvm/guest/init_stage2.c b/tools/kvm/guest/init_stage2.c new file mode 100644 index 000000000000..af615a007839 --- /dev/null +++ b/tools/kvm/guest/init_stage2.c @@ -0,0 +1,34 @@ +/* + * This is a stage 2 of the init. This part should do all the heavy + * lifting such as setting up the console and calling /bin/sh. + */ +#include +#include +#include +#include +#include + +static int run_process(char *filename) +{ + char *new_argv[] = { filename, NULL }; + char *new_env[] = { "TERM=linux", NULL }; + + return execve(filename, new_argv, new_env); +} + +int main(int argc, char *argv[]) +{ + /* get session leader */ + setsid(); + + /* set controlling terminal */ + ioctl(0, TIOCSCTTY, 1); + + puts("Starting '/bin/sh'..."); + + run_process("/bin/sh"); + + printf("Init failed: %s\n", strerror(errno)); + + return 0; +} -- 2.39.5