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Re: [Xen-devel] [PING for 4.5][PATCH v5 0/1] Add mmio_hole_size (was Add pci_hole_min_size)

From: Don Slutz [dslutz@xxxxxxxxxxx]
Sent: Thursday, September 11, 2014 12:20 PM
To: xen-devel@xxxxxxxxxxxxx
Cc: Stefano Stabellini; Boris Ostrovsky; Ian Jackson; Ian Campbell; Jan 
Beulich; Slutz, Donald Christopher
Subject: [PATCH v5 0/1] Add mmio_hole_size (was Add pci_hole_min_size)

Changes from v4 to v5:

Changes from v3 to v4:

  Jan Beulich:
    Add ignore to hvmloader message
    Adjust commit message
    Dropped min; stopped mmio_hole_size changing in hvmloader

Open question: Should I switch this to max_ram_below_4g or stay with

This may help or fix http://bugs.xenproject.org/xen/bug/28

Changes from v2 to v3:
  Dropped RFC since QEMU change will be in QEMU 2.1.0 release.

  Dropped "if (dom_info.debug)" in parse_config_data()
  since dom_info no long passed in.

  Lots more bounds checking.  Since QEMU is a min(qemu_limit,
  max_ram_below_4g) adjust code the do the same.

  Boris Ostrovsky:
    More in commit message.

Changes from v1 to v2:
  Boris Ostrovsky:
    Need to init pci_hole_min_size

  Changed the qemu name from pci_hole_min_size to

  Did not change the Xen version for now.

  Added quick note to xl.cfg.pod.5

  Added a check for a too big value. (Most likely in the wrong

If you add enough PCI devices then all mmio may not fit below 4G
which may not be the layout the user wanted. This allows you to
increase the below 4G address space that PCI devices can use and
therefore in more cases not have any mmio that is above 4G.

There are real PCI cards that do not support mmio over 4G, so if you
want to emulate them precisely, you may also need to increase the
space below 4G for them. There are drivers for these cards that also
do not work if they have their mmio space mapped above 4G.

This is posted as an RFC because you need the upstream version of
qemu with all 4 patches:


This allows growing the pci_hole to the size needed.

This may help with using pci passthru and HVM.

Don Slutz (1):
  Add mmio_hole_size

 docs/man/xl.cfg.pod.5             | 12 +++++++
 tools/firmware/hvmloader/config.h |  1 -
 tools/firmware/hvmloader/pci.c    | 71 +++++++++++++++++++++++++++------------
 tools/libxc/xc_hvm_build_x86.c    | 30 +++++++++++++++--
 tools/libxc/xenguest.h            | 11 ++++++
 tools/libxl/libxl.h               |  5 +++
 tools/libxl/libxl_create.c        | 29 ++++++++++++----
 tools/libxl/libxl_dm.c            | 24 +++++++++++--
 tools/libxl/libxl_dom.c           |  3 +-
 tools/libxl/libxl_types.idl       |  1 +
 tools/libxl/xl_cmdimpl.c          | 13 +++++++
 11 files changed, 166 insertions(+), 34 deletions(-)


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