[Minios-devel] Sharing pages between two mini-os

[Ariani A <b.noushin7@xxxxxxxxx>]

Hi all,

I want to implement shared memory mechanism between two mini-os. I started by implementing the example "4.5. Exercise: Sharing Memory between VMs" of the book "The Definitive Guide to Xen Hypervisor" . I have included the necessary files, but when I compile  "offering.c", it gives this error:

error: incompatible types when assigning to type ‘__guest_handle_ulong’ from type ‘struct grant_entry_t *’

     setup_op.frame_list = grant_table;

If I use casting for grant_table, like implementing this way:

setup_op.frame_list = (XEN_GUEST_HANDLE(ulong))grant_table;

The error will be:

error: conversion to non-scalar type requested

     setup_op.frame_list = (XEN_GUEST_HANDLE(ulong))grant_table;

..................................................................................

Can anybody help me what is wrong with this implementation?

I will post the offering.c code here:

#include "../../xen/include/public/xen.h"

#include <mini-os/os.h>

#include <mini-os/lib.h>

#include <mini-os/xmalloc.h>

#include <errno.h>

#include <xen/grant_table.h>

#include <inttypes.h>

#include <mini-os/gntmap.h>

#include <mini-os/mm.h>

#include <mini-os/gnttab.h>

#include <mini-os/semaphore.h>

//#include <xen/xen/include/public/grant_table.h>

extern void * shared_page;

extern grant_entry_t * grant_table;

void offer_page(void)

{   

    uint16_t flags;

    /* Create the grant table */

    gnttab_setup_table_t setup_op;

    setup_op.dom = DOMID_SELF;

    setup_op.nr_frames = 1;

    setup_op.frame_list = (XEN_GUEST_HANDLE(ulong))grant_table;

    //setup_op.frame_list = grant_table;

    HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup_op, 1);

    /* Offer the grant */

    grant_table[0].domid = DOMID_FRIEND;

    grant_table[0].frame = shared_page >> 12;

    flags = GTF_permit_access & GTF_reading & GTF_writing;

    grant_table[0].flags = flags;

} 

Thanks

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