Re: [Qemu-devel] [PATCH 10/13] target-ppc: Don't use hwaddr to represent hardware state

[Alexander Graf]

On 04.12.2012, at 03:42, David Gibson wrote:

> The hwaddr type is somewhat vaguely defined as being able to contain bus
> addresses on the widest possible bus in the system.  For that reason it's
> discouraged for representing specific pieces of persistent hardware state,
> which should instead use an explicit width type that matches the bits
> available in real hardware.  In particular, because of the possibility that
> the size of hwaddr might change if different buses are added to the target
> in future, it's not suitable for use in vm state descriptions for savevm
> and migration.
> 
> This patch purges such unwise uses of hwaddr from the ppc target code,
> which turns out to be just one.  The ppcemb_tlb_t struct, used on a number
> of embedded ppc models to represent a TLB entry contains a hwaddr for the
> real address field.  This patch changes it to be a fixed uint64_t which is
> suitable enough for all machine types which use this structure.
> 
> Other uses of hwaddr in CPUPPCState turn out not to be problematic:
> htab_base and htab_mask are just used for the convenience of the TCG code;
> the underlying machine state is the SDR1 register, which is stored with
> a suitable type already.  Likewise the mpic_cpu_base field is only used
> internally and does not represent fundamental hardware state which needs to
> be saved.
> 
> Signed-off-by: David Gibson <address@hidden>

Thanks, applied to ppc-next.


Alex