In the absence of /init and other nice boot goodies, we fall through to
prepare_namespace() so we shall require initmem to complete boot.
Freeing 1nunedlketo lamdlo y:r3elkpfgeeg
equest at virtual address c06c22a0
printing eip:
c06c22a0
*pde = 00757027
Oops: 0000 [#1]
PREEMPT SMP DEBUG_PAGEALLOC
CPU: 1
EIP: 0060:[<c06c22a0>] Not tainted VLI
EFLAGS: 00010213 (2.6.5-rc2-mm1)
EIP is at prepare_namespace+0x0/0xd0
eax: 00000002 ebx: 00000000 ecx: c060b2c0 edx: c060b300
esi: 00000001 edi: 00000000 ebp: dff8ffec esp: dff8ffd4
ds: 007b es: 007b ss: 0068
Process swapper (pid: 1, threadinfo=dff8f000 task=dff1fa50)
Stack: c0103235 00000000 00000000 0000007b c0103170 00000000 00000000 c01051f5
00000000 00000000 00000000
Call Trace:
[<c0103235>] init+0xc5/0x190
[<c0103170>] init+0x0/0x190
[<c01051f5>] kernel_thread_helper+0x5/0x10
Code: Bad EIP value.
<0>Kernel panic: Attempted to kill init!
Index: linux-2.6.5-rc2-mm1/init/main.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.5-rc2-mm1/init/main.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 main.c
--- linux-2.6.5-rc2-mm1/init/main.c 21 Mar 2004 17:02:18 -0000 1.1.1.1
+++ linux-2.6.5-rc2-mm1/init/main.c 21 Mar 2004 20:54:19 -0000
@@ -586,8 +586,8 @@ static int free_initmem_on_exec_helper(v
char c;
sys_close(fd[1]);
- sys_read(fd[0], &c, 1);
- free_initmem();
+ if (sys_read(fd[0], &c, 1) > 0)
+ free_initmem();
return 0;
}
@@ -596,7 +596,7 @@ static void free_initmem_on_exec(void)
int fd[2];
do_pipe(fd);
- kernel_thread(free_initmem_on_exec_helper, &fd, SIGCHLD);
+ kernel_thread(free_initmem_on_exec_helper, &fd, SIGCHLD);
sys_dup2(fd[1], 255); /* to get it out of the way */
sys_close(fd[0]);
@@ -643,6 +643,7 @@ static int init(void * unused)
run_init_process("/init");
prepare_namespace();
+ free_initmem();
if (sys_open("/dev/console", O_RDWR, 0) < 0)
printk("Warning: unable to open an initial console.\n");
Zwane Mwaikambo wrote:
>In the absence of /init and other nice boot goodies, we fall through to
>prepare_namespace() so we shall require initmem to complete boot.
>
>
>Index: linux-2.6.5-rc2-mm1/init/main.c
>===================================================================
>RCS file: /home/cvsroot/linux-2.6.5-rc2-mm1/init/main.c,v
>retrieving revision 1.1.1.1
>diff -u -p -B -r1.1.1.1 main.c
>--- linux-2.6.5-rc2-mm1/init/main.c 21 Mar 2004 17:02:18 -0000 1.1.1.1
>+++ linux-2.6.5-rc2-mm1/init/main.c 21 Mar 2004 20:54:19 -0000
>@@ -586,8 +586,8 @@ static int free_initmem_on_exec_helper(v
> char c;
>
> sys_close(fd[1]);
>- sys_read(fd[0], &c, 1);
>- free_initmem();
>+ if (sys_read(fd[0], &c, 1) > 0)
>+ free_initmem();
> return 0;
> }
>
>
But the above change makes the early init case to not free initmem,
which was the whole purpose of the close_on_exec + read + broken pipe
hassle, I think.
--Mika
On Mon, Mar 22, Zwane Mwaikambo wrote:
> In the absence of /init and other nice boot goodies, we fall through to
> prepare_namespace() so we shall require initmem to complete boot.
Andrew, please restore the previous version of the patch. The 3 liner is
much more obvious.
--
USB is for mice, FireWire is for men!
sUse lINUX ag, nÜRNBERG
On Mon, Mar 22, Zwane Mwaikambo wrote:
> On Mon, 22 Mar 2004, Olaf Hering wrote:
>
> > On Mon, Mar 22, Zwane Mwaikambo wrote:
> >
> > > In the absence of /init and other nice boot goodies, we fall through to
> > > prepare_namespace() so we shall require initmem to complete boot.
> >
> > Andrew, please restore the previous version of the patch. The 3 liner is
> > much more obvious.
>
> Olaf, what does the previous patch look like?
.../people/akpm/patches/2.6/2.6.5-rc1/2.6.5-rc1-mm1/broken-out/initramfs-search-for-init.patch
From: Olaf Hering <[email protected]>
initramfs can not be used in current 2.6 kernels, the files will never be
executed because prepare_namespace doesn't care about them. The only way to
workaround that limitation is a root=0:0 cmdline option to force rootfs as
root filesystem. This will break further booting because rootfs is not the
final root filesystem.
This patch checks for the presence of /init which comes from the cpio archive
(and thats the only way to store files into the rootfs). This binary/script
has to do all the work of prepare_namespace().
---
25-akpm/Documentation/early-userspace/README | 26 ++++++++++++++++++++++++++
25-akpm/init/main.c | 7 +++++++
2 files changed, 33 insertions(+)
diff -puN init/main.c~initramfs-search-for-init init/main.c
--- 25/init/main.c~initramfs-search-for-init Tue Mar 9 17:00:46 2004
+++ 25-akpm/init/main.c Tue Mar 9 17:00:46 2004
@@ -604,6 +604,13 @@ static int init(void * unused)
sched_init_smp();
do_basic_setup();
+ /*
+ * check if there is an early userspace init, if yes
+ * let it do all the work
+ */
+ if (sys_access("/init", 0) == 0)
+ execute_command = "/init";
+ else
prepare_namespace();
/*
diff -puN Documentation/early-userspace/README~initramfs-search-for-init Documentation/early-userspace/README
--- 25/Documentation/early-userspace/README~initramfs-search-for-init Tue Mar 9 17:00:46 2004
+++ 25-akpm/Documentation/early-userspace/README Tue Mar 9 17:00:46 2004
@@ -71,5 +71,31 @@ custom initramfs images that meet your n
For questions and help, you can sign up for the early userspace
mailing list at http://www.zytor.com/mailman/listinfo/klibc
+How does it work?
+=================
+
+The kernel has currently 3 ways to mount the root filesystem:
+
+a) all required device and filesystem drivers compiled into the kernel, no
+ initrd. init/main.c:init() will call prepare_namespace() to mount the
+ final root filesystem, based on the root= option and optional init= to run
+ some other init binary than listed at the end of init/main.c:init().
+
+b) some device and filesystem drivers built as modules and stored in an
+ initrd. The initrd must contain a binary '/linuxrc' which is supposed to
+ load these driver modules. It is also possible to mount the final root
+ filesystem via linuxrc and use the pivot_root syscall. The initrd is
+ mounted and executed via prepare_namespace().
+
+c) using initramfs. The call to prepare_namespace() must be skipped.
+ This means that a binary must do all the work. Said binary can be stored
+ into initramfs either via modifying usr/gen_init_cpio.c or via the new
+ initrd format, an cpio archive. It must be called "/init". This binary
+ is responsible to do all the things prepare_namespace() would do.
+
+ To remain backwards compatibility, the /init binary will only run if it
+ comes via an initramfs cpio archive. If this is not the case,
+ init/main.c:init() will run prepare_namespace() to mount the final root
+ and exec one of the predefined init binaries.
Bryan O'Sullivan <[email protected]>
_
--
USB is for mice, FireWire is for men!
sUse lINUX ag, nÜRNBERG
On Mon, 22 Mar 2004, Olaf Hering wrote:
> On Mon, Mar 22, Zwane Mwaikambo wrote:
>
> > In the absence of /init and other nice boot goodies, we fall through to
> > prepare_namespace() so we shall require initmem to complete boot.
>
> Andrew, please restore the previous version of the patch. The 3 liner is
> much more obvious.
Olaf, what does the previous patch look like?