The MSI capture logic for the axon bridge can sometimes
lose interrupts in case of high DMA and interrupt load,
when it signals an MSI interrupt to the MPIC interrupt
controller while we are already handling another MSI.

Each MSI vector gets written into a FIFO buffer in main
memory using DMA, and that DMA access is normally flushed
by the actual interrupt packet on the IOIF.  An MMIO
register in the MSIC holds the position of the last
entry in the FIFO buffer that was written.  However,
reading that position does not flush the DMA, so that
we can observe stale data in the buffer.

In a stress test, we have observed the DMA to arrive
up to 14 microseconds after reading the register.

This patch works around this problem by retrying the
access to the FIFO buffer.

We can reliably detect the conditioning by writing
an invalid MSI vector into the FIFO buffer after
reading from it, assuming that all MSIs we get
are valid.  After detecting an invalid MSI vector,
we udelay(1) in the interrupt cascade for up to
100 times before giving up.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

I got a bug report about a distro kernel not booting on a particular
machine.  It would freeze during boot:

> ...
> Could not find start_pfn for node 1
> [boot]0015 Setup Done
> Built 2 zonelists in Node order, mobility grouping on.  Total pages: 123783
> Policy zone: DMA
> Kernel command line:
> [boot]0020 XICS Init
> [boot]0021 XICS Done
> PID hash table entries: 4096 (order: 12, 32768 bytes)
> clocksource: timebase mult[7d0000] shift[22] registered
> Console: colour dummy device 80x25
> console handover: boot [udbg0] -> real [hvc0]
> Dentry cache hash table entries: 1048576 (order: 7, 8388608 bytes)
> Inode-cache hash table entries: 524288 (order: 6, 4194304 bytes)
> freeing bootmem node 0

I've reproduced this on 2.6.27.7.  It is caused by commit
8f64e1f2 ("powerpc: Reserve in bootmem
lmb reserved regions that cross NUMA nodes").

The problem is that Jon took a loop which was (in pseudocode):

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
		reserve_node_bootmem(nid);

and broke it up into:

	for_each_node(nid)
		NODE_DATA(nid) = careful_alloc(nid);
		setup_bootmem(nid);
	for_each_node(nid)
		reserve_node_bootmem(nid);

The issue comes in when the 'careful_alloc()' is called on a node with
no memory.  It falls back to using bootmem from a previously-initialized
node.  But, bootmem has not yet been reserved when Jon's patch is
applied.  It gives back bogus memory (0xc000000000000000) and pukes
later in boot.

The following patch collapses the loop back together.  It also breaks
the mark_reserved_regions_for_nid() code out into a function and adds
some comments.  I think a huge part of introducing this bug is because
for loop was too long and hard to read.

The actual bug fix here is the:

+		if (end_pfn <= node->node_start_pfn ||
+		    start_pfn >= node_end_pfn)
+			continue;
Signed-off-by: NDave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Currently, some PCIe devices on POWER6 machines do not get interrupts
assigned correctly.  The problem is that OF doesn't create an
"interrupt" property for them.  The fix is for of_irq_map_pci to fall
back to using the value in the PCI interrupt-pin register in config
space, as we do when there is no OF device-tree node for the device.

I have verified that this works fine with a pair of Squib-E SAS
adapter on a P6-570.
Acked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Currently, we can end up in an infinite loop if we get a signal
while the kernel has faulted in spufs_ps_fault. Eg:

 alarm(1);

 write(fd, some_spu_psmap_register_address, 4);

- the write's copy_from_user will fault on the ps mapping, and
signal_pending will be non-zero. Because returning from the fault
handler will never clear TIF_SIGPENDING, so we'll just keep faulting,
resulting in an unkillable process using 100% of CPU.

This change returns VM_FAULT_SIGBUS if there's a fatal signal pending,
letting us escape the loop.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>

ethernet0 (called FSL UEC0 in U-Boot) should be enet1 (UCC3/eth1), and
ethernet1 should be enet0 (UCC2/eth0), to be consistent with U-Boot so
that the interfaces do not swap addresses when control passes from
U-Boot to the kernel.
Signed-off-by: NMichael Barkowski <michael.barkowski@freescale.com>
Acked-by: NKim Phillips <kim.phillips@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

The Marvell PHY driver is currently being used for the 88E1111 on the
SBC610. This driver is causing the link to run in 10/Half mode, the generic
PHY driver is correctly configuring the PHY as 1000/Full.

Edit default config to use generic PHY driver.
Signed-off-by: NMartyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

It's 1MB, not 512KB.  Newer U-Boots will fix this entry, but that's no
reason to have the wrong value in the dts.
Signed-off-by: NTrent Piepho <tpiepho@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Update defconfigs for running on Xilinx Virtex platforms
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

Various printk format string in code used by the Xilinx Virtex platform
are not 32-bit/64-bit safe.  Add correct casting to fix the bugs.
Reported-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

Without this patch it is possible to select drivers which require
bestcomm support without bestcomm support being selected.  This
patch reworks the bestcomm dependencies to ensure the correct
bestcomm tasks are always enabled.
Reported-by: NHans Lehmann <hans.lehmann@ritter-elektronik.de>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

Those cores use the 440A type machine check (ie, they have
MCSRR0/MCSRR1). They thus need to call the appropriate fixup
function to hook the right variant of the exception.

Without this, all machine checks become fatal due to loss
of context when entering the exception handler.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

If the size of DRAM is not an exact power of two, we may not have
covered DRAM in its entirety with large 16 and 4 MiB pages.  If that
is the case, we can get non-recoverable page faults when doing the
final PTE mappings for the non-large page PTEs.

Consequently, we restrict the top end of DRAM currently allocable
by updating '__initial_memory_limit_addr' so that calls to the LMB to
allocate PTEs for "tail" coverage with normal-sized pages (or other
reasons) do not attempt to allocate outside the allowed range.
Signed-off-by: NGrant Erickson <gerickson@nuovations.com>
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

Turned off CONFIG_PCI_LEGACY and turned on EXT4, and otherwise mostly
took the defaults.  This also updates ppc6xx_defconfig, which covers
the 6xx/7xx/7xxx-based embedded boards.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The new context may not be 16-byte aligned, so the real address of the
mcontext structure should be read from the uc_regs pointer instead of
directly using the (unaligned) uc_mcontext field.
Signed-off-by: NAndreas Schwab <schwab@suse.de>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

unset CONFIG_PCI_LEGACY in the defconfigs as none of them enable
ISDN drivers which seem to be the only place we are using pci_find_device
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

Fixes following build error:

  CC      drivers/usb/gadget/fsl_qe_udc.o
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_eprx_stall_change':
drivers/usb/gadget/fsl_qe_udc.c:156: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c:163: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_eptx_stall_change':
drivers/usb/gadget/fsl_qe_udc.c:173: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c:180: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_eprx_nack':
drivers/usb/gadget/fsl_qe_udc.c:201: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c:201: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_eprx_normal':
drivers/usb/gadget/fsl_qe_udc.c:218: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c:218: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_ep_reset':
drivers/usb/gadget/fsl_qe_udc.c:325: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c:342: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'qe_ep_register_init':
drivers/usb/gadget/fsl_qe_udc.c:515: error: 'struct usb_ctlr' has no member named 'usb_usep'
drivers/usb/gadget/fsl_qe_udc.c: In function 'ch9getstatus':
drivers/usb/gadget/fsl_qe_udc.c:1981: error: 'struct usb_ctlr' has no member named 'usb_usep'
make[2]: *** [drivers/usb/gadget/fsl_qe_udc.o] Error 1
Signed-off-by: NLi Yang <leoli@freescale.com>
Signed-off-by: NAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

This patch corrects the bus-frequency value provided in the SBC610's dts.
Signed-off-by: NMartyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

The implemetation of _tlbil_pid() on Freescale Book-E cores needs
an msync & isync after we flash invalidate the TLBs.  This was causing
the following oops reported by Sebastian Andrzej Siewior:

  VFS: Mounted root (nfs filesystem) readonly.
  Freeing unused kernel memory: 148k init
  BUG: sleeping function called from invalid context at /home/bigeasy/git/linux-2.6-powerpc/mm/mmap.c:234
  in_atomic():1, irqs_disabled():0
  Call Trace:
  [df189df0] [c0007160] show_stack+0x48/0x148 (unreliable)
  [df189e30] [c0029480] __might_sleep+0xf0/0x100
  [df189e40] [c0070ac0] remove_vma+0x28/0x98
  [df189e50] [c0070c1c] exit_mmap+0xec/0x128
  [df189e80] [c002d2f4] mmput+0x54/0xec
  [df189ea0] [c0030b6c] exit_mm+0x10c/0x120
  [df189ed0] [c003288c] do_exit+0x1ac/0x6e8
  [df189f20] [c0032e48] do_group_exit+0x80/0xac
  [df189f40] [c000e9dc] ret_from_syscall+0x0/0x3c
  BUG: scheduling while atomic: udevd/956/0x10000002
  Modules linked in:
  Call Trace:
  [df189df0] [c0007160] show_stack+0x48/0x148 (unreliable)
  [df189e30] [c002ac88] __schedule_bug+0x58/0x6c
  [df189e40] [c023e6cc] schedule+0xa8/0x4a8
  [df189e90] [c002ad6c] __cond_resched+0x38/0x64
  [df189ea0] [c023ebc8] _cond_resched+0x3c/0x58
  [df189eb0] [c0030e70] put_files_struct+0x90/0xec
  [df189ed0] [c00328a8] do_exit+0x1c8/0x6e8
  [df189f20] [c0032e48] do_group_exit+0x80/0xac
  [df189f40] [c000e9dc] ret_from_syscall+0x0/0x3c
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

This gets rid of this build warning:

arch/powerpc/platforms/pseries/pci_dlpar.c: In function 'init_phb_dynamic':
arch/powerpc/platforms/pseries/pci_dlpar.c:192: warning: unused variable 'b'

This is one of the very few warnings left in a ppc64_defconfig build and
getting rid of it will make it easier to see future introduced ones (in
fact this was introduced very recently).
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This fixes this error on Cell when CONFIG_KEXEC = n:

arch/powerpc/platforms/cell/ras.c:299: error: implicit declaration of function 'crash_shutdown_register'

We have to include <asm/kexec.h> because it contains the dummy
definition of crash_shutdown_register that is used when
CONFIG_KEXEC=n, but <linux/kexec.h> doesn't include <asm/kexec.h> in
that case.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Updated the patch to address comments by Michael Ellerman.
Specifically, changed upper limit in for loop to
ARRAY_SIZE() macro and added a check to make sure the
number of events specified by the user, which is used as
the max for indexing various arrays, is no bigger then the
declared size of the arrays.

The size of the pm_signal_local array should be equal to the
number of SPUs being configured in the array.  Currently, the
array is of size 4 (NR_PHYS_CTRS) but being indexed by a for
loop from 0 to 7 (NUM_SPUS_PER_NODE).
Signed-off-by: NCarl Love <carll@us.ibm.com>

This reverts commit fa448d60.

This reverts commit 91a00302, plus
commit 0dcd4401 ("powerpc: Revert CHRP
boot wrapper to real-base = 12MB on 32-bit") which depended on it.

Commit 91a00302 was causing NVRAM corruption on some pSeries machines,
for as-yet unknown reasons, so this reverts it until the cause is
identified.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

This makes sure we don't try to call find_bug or is_warning_bug when
CONFIG_BUG=n and CONFIG_XMON=y.  Otherwise we get these errors:

arch/powerpc/xmon/xmon.c: In function ‘print_bug_trap’:
arch/powerpc/xmon/xmon.c:1364: error: implicit declaration of function ‘find_bug’
arch/powerpc/xmon/xmon.c:1364: warning: assignment makes pointer from integer without a cast
arch/powerpc/xmon/xmon.c:1367: error: implicit declaration of function ‘is_warning_bug’
arch/powerpc/xmon/xmon.c:1374: error: dereferencing pointer to incomplete type
make[2]: *** [arch/powerpc/xmon/xmon.o] Error 1
make[1]: *** [arch/powerpc/xmon] Error 2
make: *** [sub-make] Error 2
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Fix format string warning in arch/powerpc/boot/main.c.  Also correct
a typo ("uncomressed") on the same line.

 BOOTCC  arch/powerpc/boot/main.o
arch/powerpc/boot/main.c: In function 'prep_kernel':
arch/powerpc/boot/main.c:65: warning: format '%08x' expects type
'unsigned int', but argument 3 has type 'long unsigned int'
Signed-off-by: NJon Smirl <jonsmirl@gmail.com>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

There's currently an off-by-one bug in fdt_subnode_offset_namelen()
which causes it to keep searching after it's finished the subnodes of
the given parent, and into the subnodes of siblings of the original
node which come after it in the tree.  This bug was introduced in
commit ed95d745 ("powerpc: Update
in-kernel dtc and libfdt to version 1.2.0").

A patch has already been submitted to dtc/libfdt mainline.  We don't
really want to pull in a new upstream version during the 2.6.28 cycle,
but we should still fix this bug, hence this standalone version of the
fix for the in-kernel libfdt.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Commit 57436612 added a duplicate
DMA controller node.
Signed-off-by: NMike Dyer <mike.dyer@provision-comm.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

The size of the pm_signal_local array should be equal to the
number of SPUs being configured in the array.  Currently, the
array is of size 4 (NR_PHYS_CTRS) but being indexed by a for
loop from 0 to 7 (NUM_SPUS_PER_NODE).  This could potentially
cause an oops or random memory corruption since the pm_signal_local
array is on the stack.  This fixes it.
Signed-off-by: NCarl Love <carll@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The Freescale implementation of MPIC only allows a single CPU destination
for non-IPI interrupts.  We add a flag to the mpic_init to distinquish
these variants of MPIC.  We pull in the irq_choose_cpu from sparc64 to
select a single CPU as the destination of the interrupt.

This is to deal with the fact that the default smp affinity was
changed by commit 18404756 ("genirq:
Expose default irq affinity mask (take 3)") to be all CPUs.
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

After the merge of the 32 and 64bit DMA code, dma_direct_ops lost
their map/unmap_single() functions but gained map/unmap_page().  This
caused a problem for Cell because Cell's dma_iommu_fixed_ops called
the dma_direct_ops if the fixed linear mapping was to be used or the
iommu ops if the dynamic window was to be used.  So in order to fix
this problem we need to update the 64bit DMA code to use
map/unmap_page.

First, we update the generic IOMMU code so that iommu_map_single()
becomes iommu_map_page() and iommu_unmap_single() becomes
iommu_unmap_page().  Then we propagate these changes up through all
the callers of these two functions and in the process update all the
dma_mapping_ops so that they have map/unmap_page rahter than
map/unmap_single.  We can do this because on 64bit there is no HIGHMEM
memory so map/unmap_page ends up performing exactly the same function
as map/unmap_single, just taking different arguments.

This has no affect on drivers because the dma_map_single_attrs() just
ends up calling the map_page() function of the appropriate
dma_mapping_ops and similarly the dma_unmap_single_attrs() calls
unmap_page().

This fixes an oops on Cell blades, which oops on boot without this
because they call dma_direct_ops.map_single, which is NULL.
Signed-off-by: NMark Nelson <markn@au1.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

A typo/thinko made us pass the wrong argument to __flush_hash_table_range
when unplugging bridges, thus not flushing all the translations for
the IO space on unplug.  The third parameter to __flush_hash_table_range
is `end', not `size'.

This causes the hypervisor to refuse unplugging slots.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Resources for PHB's that are dynamically added to a system are not
properly allocated in the resource tree.

Not having these resources allocated causes an oops when removing
the PHB when we try to release them.

The diff appears a bit messy, this is mainly due to moving everything
one tab to the left in the pcibios_allocate_bus_resources routine.
The functionality change in this routine is only that the
list_for_each_entry() loop is pulled out and moved to the necessary
calling routine.
Signed-off-by: NNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Currently, the numa_node of OF-devices will be overwritten during
device_register, which simply sets the node to -1.  On cell machines,
this means that devices can't find their IOMMU, which is referenced
through the device's numa node.

Set the numa node for OF devices with no parent, and use the
lower-level device_initialize and device_add functions, so that the
node is preserved.

We can remove the call to set_dev_node in of_device_alloc, as it
will be overwritten during register.
Signed-off-by: NJeremy Kerr <jk@ozlabs.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Since VSX support was added, we now have two sizes of ucontext_t;
the older, smaller size without the extra VSX state, and the new
larger size with the extra VSX state.  A program using the
sys_swapcontext system call and supplying smaller ucontext_t
structures will currently get an EINVAL error if the task has
used VSX (e.g. because of calling library code that uses VSX) and
the old_ctx argument is non-NULL (i.e. the program is asking for
its current context to be saved).  Thus the program will start
getting EINVAL errors on calls that previously worked.

This commit changes this behaviour so that we don't send an EINVAL in
this case.  It will now return the smaller context but the VSX MSR bit
will always be cleared to indicate that the ucontext_t doesn't include
the extra VSX state, even if the task has executed VSX instructions.

Both 32 and 64 bit cases are updated.

[paulus@samba.org - also fix some access_ok() and get_user() calls]

Thanks to Ben Herrenschmidt for noticing this problem.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Fixes this warning:
 arch/powerpc/kernel/setup_64.c:447:5: warning: "kernstart_addr" is not defined

which arises because PHYSICAL_START is no longer a constant when
CONFIG_RELOCATABLE=y.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Commit 549e8152 ("powerpc: Make the
64-bit kernel as a position-independent executable") added lines to
vmlinux.lds.S to add the extra sections needed to implement a
relocatable kernel.  However, those lines seem to trigger a bug in
older versions of GNU ld (such as 2.16.1) when building a
non-relocatable kernel.  Since ld 2.16.1 is still a popular choice for
cross-toolchains, this adds an #ifdef to vmlinux.lds.S so the added
lines are only included when building a relocatable kernel.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

The __kdump_flag ABI is overly constraining for future development.

As of 2.6.27, the kernel entry point has 4 constraints:  Offset 0 is
the starting point for the master (boot) cpu (entered with r3 pointing
to the device tree structure), offset 0x60 is code for the slave cpus
(entered with r3 set to their device tree physical id), offset 0x20 is
used by the iseries hypervisor, and secondary cpus must be well behaved
when the first 256 bytes are copied to address 0.

Placing the __kdump_flag at 0x18 is bad because:

- It was taking the last 8 bytes before the iseries hypervisor data.
- It was 8 bytes for a boolean flag
- It had no way of identifying that the flag was present
- It does leave any room for the master to add any additional code
  before branching, which hurts debug.
- It will be unnecessarily hard for 32 bit code to be common (8 bytes)

Now that we have eliminated the use of __kdump_flag in favor of
the standard is_kdump_kernel(), this flag only controls run without
relocating the kernel to PHYSICAL_START (0), so rename it __run_at_load.

Move the flag to 0x5c, 1 word before the secondary cpu entry point at
0x60.  Initialize it with "run0" to say it will run at 0 unless it is
set to 1.  It only exists if we are relocatable.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

linux/crash_dump.h defines is_kdump_kernel() to be used by code that
needs to know if the previous kernel crashed instead of a (clean) boot
or reboot.

This updates the just added powerpc code to use it.  This is needed
for the next commit, which will remove __kdump_flag.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

Commit 54622f10 ("powerpc: Support for
relocatable kdump kernel") added a magic flag value in a register to
tell purgatory that it should be a panic kernel.  This part is wrong
and is reverted by this commit.

The kernel gets a list of memory blocks and a entry point from user space.
Its job is to copy the blocks into place and then branch to the designated
entry point (after turning "off" the mmu).

The user space tool inserts a trampoline, called purgatory, that runs
before the user supplied code.   Its job is to establish the entry
environment for the new kernel or other application based on the contents
of memory.  The purgatory code is compiled and embedded in the tool,
where it is later patched using the elf symbol table using elf symbols.

Since the tool knows it is creating a purgatory that will run after a
kernel crash, it should just patch purgatory (or the kernel directly)
if something needs to happen.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>