Re: [Qemu-devel] [RFC 13/38] cputlb: add physical address to CPUTLBEntry

[Paolo Bonzini]

On 24/08/2015 02:23, Emilio G. Cota wrote:
> Having the physical address in the TLB entry will allow us
> to portably obtain the physical address of a memory access,
> which will prove useful when implementing a scalable emulation
> of atomic instructions.

It came to my mind that addr_read and addr_code only differ in the
bottom TARGET_PAGE_BITS bits, and they are always zero in addr_phys.

So we could store addr_code as

   addr_read ^ (addr_phys & (TARGET_PAGE_SIZE - 1))

and discard the bottom bits of addr_phys.  This would make it possible
to include addr_phys without growing the size of the TLB entry.

Paolo