[Xen-devel] [PATCH] Make ballooning work with maxmem > mem (i386 version)

[Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>]

Trying to start a guest with maxmem > mem and then balloon up to a value
greater than mem is currently failing. This have been already discovered
(patch sent some days ago) for x86_64. i386 suffers from the same
problem.

This patch fixes it.

-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

# HG changeset patch
# User Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>
# Node ID 2e2e6a3f9b2d0ad21c666dfbdc075f918e0bc7be
# Parent  20204db0891b0b7c10959822e3283656c3600500
[LINUX] Extend physical mapping to maxmem instead of mem - i386 version

As currently physical mapping only reaches the initial reservation,
we're unable to balloon up to more than mem (even when maxmem > mem)
in any situation. This have already been found out to be broken and fixed
in x86_64

Signed-off-by: Glauber de Oliveira Costa <gcosta@xxxxxxxxxx>

diff -r 20204db0891b -r 2e2e6a3f9b2d 
linux-2.6-xen-sparse/include/asm-i386/mach-xen/setup_arch_post.h
--- a/linux-2.6-xen-sparse/include/asm-i386/mach-xen/setup_arch_post.h  Thu Nov 
 2 18:52:04 2006
+++ b/linux-2.6-xen-sparse/include/asm-i386/mach-xen/setup_arch_post.h  Fri Nov 
10 13:14:14 2006
@@ -13,6 +13,7 @@
 {
        int rc;
        struct xen_memory_map memmap;
+       unsigned long arg = DOMID_SELF;
        /*
         * This is rather large for a stack variable but this early in
         * the boot process we know we have plenty slack space.
@@ -26,6 +27,11 @@
        if ( rc == -ENOSYS ) {
                memmap.nr_entries = 1;
                map[0].addr = 0ULL;
+               rc = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &arg);
+               if ( rc < 0 )
+                       map[0].size = PFN_PHYS(xen_start_info->nr_pages);
+               else
+                       map[0].size = PFN_PHYS(rc);
                map[0].size = PFN_PHYS(xen_start_info->nr_pages);
                /* 8MB slack (to balance backend allocations). */
                map[0].size += 8ULL << 20;

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