Re: [patch 4/5] ia64: fail mmaps that span areas with incompatible attributes

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Sunday 27 May 2007 08:55:45 pm Peter Chubb wrote:
> >>>>> "Peter" = Peter Chubb <peter@chubb.wattle.id.au> writes:
> 
> >>>>> "Bjorn" = Bjorn Helgaas <bjorn.helgaas@hp.com> writes:
> 
> Bjorn> Example memory map (from HP sx1000 with VGA enabled): 0x00000 -
> Bjorn> 0x9FFFF supports only WB (cacheable) access 0xA0000 - 0xBFFFF
> Bjorn> supports only UC (uncacheable) access 0xC0000 - 0xFFFFF
> Bjorn> supports only WB (cacheable) access
> 
> Bjorn> Some versions of X map the entire 0x00000-0xFFFFF area at once.
> Bjorn> With the example above, this mmap must fail because there's no
> Bjorn> memory attribute that's safe for the entire area.
> 
> Peter> This patch breaks X on a ZX2000.
> 
> Except that there is a fix in the latest X source.
> 
> Sorry to bother you all.

No problem, I should have mentioned the X server interlock
in the changelog, which would have saved you the trouble of
debugging this.  This whole area has been an incredible
headache, and I recently discovered yet another hole to
be fixed (mmap via /proc/bus/pci needs to be checked, iirc).

Bjorn