On 02/14/2011 06:33 PM, Matt Thomas wrote:
On Feb 14, 2011, at 6:22 PM, David Daney wrote:
On 02/14/2011 04:15 PM, Matt Thomas wrote:
I have to wonder if it's worth the effort. The primary problem I see
is that this new ABI requires a 64bit kernel since faults through the
upper 2G will go through the XTLB miss exception vector.
Yes, that is correct. It is a 64-bit ABI, and like the existing n32 ABI
requires a 64-bit kernel.
N32 doesn't require a LP64 kernel, just a 64-bit register aware kernel.
Your N32-big does require a LP64 kernel.
But using 'official' kernel sources the only way to get a 64-bit
register aware kernel is for it to also be LP64. So effectively, you do
in fact need a 64-bit kernel to run n32 userspace code.
My proposed ABI would need trivial kernel changes:
o Fix a couple of places where pointers are sign extended instead of
zero extended.
o Change the stack address and address ranges returned by mmap().
The main work would be in the compiler toolchain and runtime libraries.
David Daney
