From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 30 Sep 2009 15:22:41 +0200
Subject: [xen] ia64: command-line arg to increase the heap size
Message-id: 1254316961-31834-1-git-send-email-pbonzini@redhat.com
O-Subject: [RHEL5.5 PATCH v3] xen: add command-line argument increasing the xen heap size on ia64 (BZ521865)
Bugzilla: 521865
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Don Dutile <ddutile@redhat.com>

Bugzilla: 521865

Upstream: related to c/s 19109, 19129 and 19130

Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=2009109

The bug is that the amount of memory needed in the Xen heap, for a 128GB
ia64 machine, exceeds the amount of memory that is allocated at startup.

Upstream is growing the heap dynamically, which is quite an invasive
change.

In order to keep the size static, I tried determining the heap size based
on the amount of available memory, but there is a chicken-and-egg problem:
it is not possible to call efi_memmap_walk before the heap is initialized,
and efi_memmap_walk is required to find out how much memory we have.

Therefore, I added the same "xenheap_megabytes=nnn" hypervisor command-line
option that is present for other architectures.  Given the current size of
64 MB is okay for a 64 GB machine, the release notes can suggest a value
equal to the number of gigabytes of available RAM.

The patch was tested by me on hp-rx8640-03.rhts.bos.redhat.com and it
fixes the problem.

Please review and ack.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/ia64/xen/xensetup.c b/arch/ia64/xen/xensetup.c
index 9fa7e4d..7f8a4af 100644
--- a/arch/ia64/xen/xensetup.c
+++ b/arch/ia64/xen/xensetup.c
@@ -81,8 +81,10 @@ boolean_param("xencons_poll", opt_xencons_poll);
  * elilo chooses 256M as alignment when relocating, alignment issue
  * on IPF can be addressed.
  */
-unsigned int opt_xenheap_megabytes = XENHEAP_DEFAULT_MB;
-unsigned long xenheap_size = XENHEAP_DEFAULT_SIZE;
+static unsigned int opt_xenheap_megabytes = XENHEAP_DEFAULT_MB;
+integer_param("xenheap_megabytes", opt_xenheap_megabytes);
+
+unsigned long xenheap_size;
 extern long running_on_sim;
 unsigned long xen_pstart;
 void *xen_heap_start __read_mostly;
@@ -304,6 +306,7 @@ void start_kernel(void)
 
     printk("Xen command line: %s\n", saved_command_line);
     /* xenheap should be in same TR-covered range with xen image */
+    xenheap_size = opt_xenheap_megabytes << 20;
     xenheap_phys_end = xen_pstart + xenheap_size;
     printk("xen image pstart: 0x%lx, xenheap pend: 0x%lx\n",
            xen_pstart, xenheap_phys_end);