Re: In which library can I find these functions ?

[Konrad Rzeszutek Wilk <konrad@kernel.org>]

On Tue, Jan 29, 2013 at 04:59:39PM +0100, Sébastien Frémal wrote:
> Hi,
> 
> I'm trying to build a module to implement a shared memory mechanism between
> the dom0 and domU's.
> 
> To do so, I'm investigating the grant table mechanisms. I have wrote that
> code (which is supposed to be the dom0-side of a module creating and
> sharing 1 page) :
> 
> #undef __KERNEL__
> #define __KERNEL__
> 
> #undef MODULE
> #define MODULE
> 
> #include <xen/page.h>
> #include <xen/grant_table.h>
> #include <linux/gfp.h>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/init.h>
> 
> unsigned long myPage;
> 
> static int __init hello_init(void){
> //      int domB = atoi(argv[1]);
>         printk(KERN_INFO "Test sur le partage de mémoire dans Xen \n");
> 
>         if((myPage = get_zeroed_page(GFP_KERNEL))==0)
>                 printk(KERN_INFO "Zeroed page\n");
> 
>         grant_ref_t gref;
>         gref = gnttab_grant_foreign_access(1, virt_to_mfn(myPage), 0);
> 
>         if(gref < 0){
>                 printk(KERN_INFO "Grant failed\n");
>                 free_page(myPage);
>         }
>         return 0;
> }
> 
> static void __exit hello_exit(void){
>         free_page(myPage);
>         printk(KERN_INFO "Cleaning module.\n");
> }
> 
> module_init(hello_init);
> module_exit(hello_exit);
> 
> The code is compiling, but when I try to launch the insert the module, I
> get error messages :
> 
> [95265.790842] shmxen: Unknown symbol gnttab_grant_foreign_access (err 0)
> [95265.790855] shmxen: Unknown symbol xen_features (err 0)
> [95265.790865] shmxen: Unknown symbol get_phys_to_machine (err 0)
> 
> I'm searching for libraries to link with the module so it can use these
> functions but I can't find those. Can you please help me ? I searched in
> project like Xen VMSocket to look after their way of dealing the problem,
> but the Makefile doesn't point out directories containing the included
> headers or libraries having implemented functions (I don't understand how
> it's suppose to compile).

cscope is quite good at finding these things. You just need
xen/grant_table.h and xen/xen.h
> 
> I thank you for your help.
> 
> Best regards,
> 
> Fremal S.

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