linux-kernel - Re: [PATCH 001/002] scripts/mod/modpost.c: New option -E to load extra symbols

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Date:	Thu, 28 Feb 2008 10:18:39 +0100
From:	Sam Ravnborg <sam@...nborg.org>
To:	Richard Hacker <lerichi@....net>
Cc:	kai@...maschewski.name, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 001/002] scripts/mod/modpost.c: New option -E to load extra symbols

Hi Richard.

I had your first patchqueued up for this and will soon take a look
at this update.

At first quick look it looked good and I have only two comments:
1) The variable should be named KBUILD_* to fit the general namespace used
2) The new possibility should be documented in Documentation/kbuild/modules.txt

I will get back when I have given it a closer look.

PS. Please also cc: linux-kbuild@...r.kernel.org if you submit again.

	Sam

On Thu, Feb 28, 2008 at 09:40:52AM +0100, Richard Hacker wrote:
> This patch adds a new command line option -E to modpost, expecting a symbol
> file as an argument which is read prior to symbol processing. -E can be 
> supplied multiple times for as many files as is needed.
> 
> Signed-off-by: Richard Hacker <lerichi@....net>
> 
> ---
> When building kernel modules that depend on other modules not in the main 
> kernel tree, modpost complains about undefined symbols:
> # make -C /path/to/linux/kernel M=/path/to/my/module
> ...
> Building modules, stage 2.
> ....
> WARNING: "rt_copy_buf" [/home/rich/osc_etl_rtw/osc_kmod.ko] undefined!
> ...etc
> 
> This situation occurs when modpost processes the new module's symbols. When
> it finds symbols not exported by the mainline kernel, it issues this warning.
> 
> The patch adds a new command line option -E to modpost which expects a symbol
> file as an argument. The symbols listed in this file are added to modpost's
> symbol tables during startup. -E can be supplied as often as required.
> 
> This patch works together with the second patch. It introduces a new make
> variable, EXTRA_SYMBOLS, which is used when calling modpost.
> 
> I hope this patch is useful and finds its way into the kernel.
> 
> o Changes from the previous attempt:
>    - patches kernel version 2.6.24
>    - patches for scripts/mod/modpost.c and scripts/Makefile.modpost are 
>      separated
>    - the argument to -E is now a single file, not a comma separated list 
>      any more. To pass more than one file, -E is used as often as required
>    - patch 002/002 in this series introduces the Kbuild variable EXTRA_SYMBOLS
>      to scripts/Makefile.modpost that in turn calls modpost with the correct
>      -E command line arguments.
> 
> --- linux-2.6.24-vanilla/scripts/mod/modpost.c	2008-02-27 21:10:24.000000000 
> +0100
> +++ linux-2.6.24/scripts/mod/modpost.c	2008-02-27 21:14:36.000000000 +0100
> @@ -1658,8 +1658,12 @@ int main(int argc, char **argv)
>  	char *dump_write = NULL;
>  	int opt;
>  	int err;
> +	struct ext_sym_list {
> +		struct ext_sym_list *next;
> +		const char *file;
> +	} *extsym_start = NULL, *extsym_iter;
>  
> -	while ((opt = getopt(argc, argv, "i:I:mso:aw")) != -1) {
> +	while ((opt = getopt(argc, argv, "i:I:E:mso:aw")) != -1) {
>  		switch(opt) {
>  			case 'i':
>  				kernel_read = optarg;
> @@ -1668,6 +1672,14 @@ int main(int argc, char **argv)
>  				module_read = optarg;
>  				external_module = 1;
>  				break;
> +			case 'E':
> +				external_module = 1;
> +				extsym_iter =
> +					NOFAIL(malloc(sizeof(*extsym_iter)));
> +				extsym_iter->next = extsym_start;
> +				extsym_iter->file = optarg;
> +				extsym_start = extsym_iter;
> +				break;
>  			case 'm':
>  				modversions = 1;
>  				break;
> @@ -1692,6 +1704,12 @@ int main(int argc, char **argv)
>  		read_dump(kernel_read, 1);
>  	if (module_read)
>  		read_dump(module_read, 0);
> +	while (extsym_start) {
> +		read_dump(extsym_start->file, 0);
> +		extsym_iter = extsym_start->next;
> +		free(extsym_start);
> +		extsym_start = extsym_iter;
> +	}
>  
>  	while (optind < argc) {
>  		read_symbols(argv[optind++]);
--
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