lkml.org 
[lkml]   [2015]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: Differences between builtins and modules
On Tue, Feb 24, 2015 at 10:02:55PM -0300, Lucas De Marchi wrote:
> On Mon, Feb 23, 2015 at 12:51 PM, Michal Marek <mmarek@suse.cz> wrote:
> > On 2015-02-23 15:30, Lucas De Marchi wrote:
> >> My questions are:
> >> 1) should we put *all* the "modules" in the builtin index?
> >
> > You mean all *.o files that do not end up in some *.ko? That won't work,
> > because unlike module names, the names of object files are not global.
>
> I was actually meaning anything that can have a directory under
> /sys/module/. I figure we can't easily know this.

I see. Well, we could generate the .modinfo section also for builtin
object files and discard it from vmlinux later, like this:

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index ac78910..efe1798 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -683,6 +683,7 @@
EXIT_CALL \
*(.discard) \
*(.discard.*) \
+ *(.modinfo) \
}

/**
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 1c9effa..f38abfa 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -16,23 +16,17 @@
/* Chosen so that structs with an unsigned long line up. */
#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))

-#ifdef MODULE
#define __MODULE_INFO(tag, name, info) \
static const char __UNIQUE_ID(name)[] \
__used __attribute__((section(".modinfo"), unused, aligned(1))) \
= __stringify(tag) "=" info
-#else /* !MODULE */
-/* This struct is here for syntactic coherency, it is not used */
-#define __MODULE_INFO(tag, name, info) \
- struct __UNIQUE_ID(name) {}
-#endif
#define __MODULE_PARM_TYPE(name, _type) \
- __MODULE_INFO(parmtype, name##type, #name ":" _type)
+ __MODULE_INFO(parmtype, name##type, MODULE_PARAM_PREFIX #name ":" _type)

/* One for each parameter, describing how to use it. Some files do
multiple of these per line, so can't just use MODULE_INFO. */
#define MODULE_PARM_DESC(_parm, desc) \
- __MODULE_INFO(parm, _parm, #_parm ":" desc)
+ __MODULE_INFO(parm, _parm, MODULE_PARAM_PREFIX #_parm ":" desc)

struct kernel_param;

Then some script would look at the parmtype= fields in the built-in.o
files and complement the list of builtin modules. However, the question
is whether this is worth it. As far as I understand, the problem is just
the discrepancy between modules.builtin and /sys/module. In practice, no
sane tool is going to need to modprobe 'vt' or 'printk', because there
is no configuration in which these modules would exist.

> > Plus, there was IIRC an idea to teach lsmod to print builtin modules --
> > listing all *.o would make it rather useless.
>
> This was one of my ideas... to traverse /sys/module and give more
> information than we actually output right now, including builtin
> modules. However, given the fact that builtin modules only have an
> entry in /sys/module if they have params and now that I'm aware of the
> race between the creation of the directory and the initstate file, I'm
> giving up on this idea for now.

You could still print the module names from modules.builtin(.idx). But
this is an unrelated topic, I only brought it up because I did not
understand what you were proposing.

Michal


\
 
 \ /
  Last update: 2015-02-25 13:21    [W:0.078 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site