qemu-xen: remove i386-dm/README.hvm-pv-magic-ioport-disable

I have just proposed a patch to add this to xen-unstable.hg as
docs/misc/hvm-emulated-unplug.markdown. This repo is not a place where people
look for docs, plus we are transitioning to upstream qemu.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/i386-dm/README.hvm-pv-magic-ioport-disable b/i386-dm/README.hvm-pv-magic-ioport-disable
deleted file mode 100644 (file)
index 142394a..0000000
--- a/i386-dm/README.hvm-pv-magic-ioport-disable
+++ /dev/null
@@ -1,70 +0,0 @@
-MAGIC IOPORT 0x10 PROTOCOL
-
-The protocol covers three basic things:
-
--- Disconnecting emulated devices.
--- Getting log messages out of the drivers and into dom0.
--- Allowing dom0 to block the loading of specific drivers.  This is
-   intended as a backwards-compatibility thing: if we discover a bug
-   in some old version of the drivers, then rather than working around
-   it in Xen, we have the option of just making those drivers fall
-   back to emulated mode.
-
-The current protocol works like this (from the point of view of
-drivers):
-
-1) When the drivers first come up, they check whether the unplug logic
-   is available by reading a two-byte magic number from IO port 0x10.
-   These should be 0x49d2.  If the magic number doesn't match, the
-   drivers don't do anything.
-
-2) The drivers read a one-byte protocol version from IO port 0x12.  If
-   this is 0, skip to 6.
-
-3) The drivers write a two-byte product number to IO port 0x12.  At
-   the moment, the only drivers using this protocol are our
-   closed-source ones, which use product number 1.
-
-4) The drivers write a four-byte build number to IO port 0x10.
-
-5) The drivers check the magic number by reading two bytes from 0x10
-   again.  If it's changed from 0x49d2 to 0xd249, the drivers are
-   blacklisted and should not load.
-
-6) The drivers write a two-byte bitmask of devices to unplug to IO
-   port 0x10.  The defined fields are:
-
-   1 -- All IDE disks (not including CD drives)
-   2 -- All emulated NICs
-   4 -- All IDE disks except for the primary master (not including CD
-       drives)
-
-   The relevant emulated devices then disappear from the relevant
-   buses.  For most guest operating systems, you want to do this
-   before device enumeration happens.
-
-...) Once the drivers have checked the magic number, they can send log
-     messages to qemu which will be logged to wherever qemu's logs go
-     (/var/log/xen/qemu-dm.log on normal Xen, dom0 syslog on
-     XenServer).  These messages are written to IO port 0x12 a byte at
-     a time, and are terminated by newlines.  There's a fairly
-     aggressive rate limiter on these messages, so they shouldn't be
-     used for anything even vaguely high-volume, but they're rather
-     useful for debugging and support.
-
-     It is still permitted for a driver to use this logging feature if
-     it is blacklisted, but ONLY if it has checked the magic number
-     and found it to be 0x49d2 or 0xd249.
-
-This isn't exactly a pretty protocol, but it does solve the problem.
-
-
-The blacklist is, from qemu's point of view, handled mostly through
-xenstore.  A driver version is considered to be blacklisted if
-/mh/driver-blacklist/{product_name}/{build_number} exists and is
-readable, where {build_number} is the build number from step 4 as a
-decimal number.  {product_name} is a string corresponding to the
-product number in step 3.
-
-The master registry of product names and numbers is in
-qemu-xen-unstable's xenstore.c.