IO resource and ioremap debugging uncovered this ioremap() done
by drivers/pci/hotplug/ibmphp_ebda.c:

initcall pci_hotplug_init+0x0/0x41 returned 0 after 3 msecs
calling  ibmphp_init+0x0/0x360 @ 1
ibmphpd: IBM Hot Plug PCI Controller Driver version: 0.6
resource map sanity check conflict: 0x9f800 0xaf5e7 0x9f800 0x9ffff reserved
------------[ cut here ]------------
WARNING: at arch/x86/mm/ioremap.c:175 __ioremap_caller+0x5c/0x226()
Pid: 1, comm: swapper Not tainted 2.6.27-rc7-tip-00914-g347b10f-dirty #36038
 [<c013a72d>] warn_on_slowpath+0x41/0x68
 [<c0156f00>] ? __lock_acquire+0x9ba/0xa7f
 [<c012158c>] ? do_flush_tlb_all+0x0/0x59
 [<c015ac31>] ? smp_call_function_mask+0x74/0x17d
 [<c012158c>] ? do_flush_tlb_all+0x0/0x59
 [<c013b228>] ? printk+0x1a/0x1c
 [<c013f302>] ? iomem_map_sanity_check+0x82/0x8c
 [<c0a773e8>] ? _read_unlock+0x22/0x25
 [<c013f302>] ? iomem_map_sanity_check+0x82/0x8c
 [<c0154e17>] ? trace_hardirqs_off+0xb/0xd
 [<c0127731>] __ioremap_caller+0x5c/0x226
 [<c0156158>] ? trace_hardirqs_on+0xb/0xd
 [<c012767d>] ? iounmap+0x9d/0xa5
 [<c01279dd>] ioremap_nocache+0x15/0x17
 [<c0403c42>] ? ioremap+0xd/0xf
 [<c0403c42>] ioremap+0xd/0xf
 [<c0f1928f>] ibmphp_access_ebda+0x60/0xa0e
 [<c0f17f64>] ibmphp_init+0xb5/0x360
 [<c0101057>] do_one_initcall+0x57/0x138
 [<c0f17eaf>] ? ibmphp_init+0x0/0x360
 [<c0156158>] ? trace_hardirqs_on+0xb/0xd
 [<c0148d75>] ? __queue_work+0x2b/0x30
 [<c0f17eaf>] ? ibmphp_init+0x0/0x360
 [<c0f015a0>] kernel_init+0x17b/0x1e2
 [<c0f01425>] ? kernel_init+0x0/0x1e2
 [<c01178b3>] kernel_thread_helper+0x7/0x10
 =======================
---[ end trace a7919e7f17c0a725 ]---
initcall ibmphp_init+0x0/0x360 returned -19 after 144 msecs
calling  zt5550_init+0x0/0x6a @ 1

the problem is this code:

        io_mem = ioremap (ebda_seg<<4, 65000);

it assumes that the EBDA is 65000 bytes. But BIOS EBDA pointers are
at most 1K large.

_if_ the Rio code truly extends upon the customary EBDA size it needs
to iounmap() this memory and ioremap() it larger, once it knows it from
the generic descriptors that a Rio system is around.

Signed-off-by: Ingo Molnar <mingo@elte.hu>