From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad@kernel.org>
Subject: Re: In which library can I find these functions ?
Date: Wed, 30 Jan 2013 16:30:05 -0500
Message-ID: <20130130213003.GB1885@konrad-lan.dumpdata.com>
References: <CAOV6k-AKbGPgx0m0yWj6ZKL0YBGn1j_nJZrMYGDnWUJ=YZ452w@mail.gmail.com>
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To: =?iso-8859-1?Q?S=E9bastien_Fr=E9mal?= <sebastien.fremal@gmail.com>
Cc: xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

On Tue, Jan 29, 2013 at 04:59:39PM +0100, S=E9bastien Fr=E9mal wrote:
> Hi,
> =

> I'm trying to build a module to implement a shared memory mechanism betwe=
en
> 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 =3D atoi(argv[1]);
>         printk(KERN_INFO "Test sur le partage de m=E9moire dans Xen \n");
> =

>         if((myPage =3D get_zeroed_page(GFP_KERNEL))=3D=3D0)
>                 printk(KERN_INFO "Zeroed page\n");
> =

>         grant_ref_t gref;
>         gref =3D 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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