Re: [Qemu-devel] [PATCH 07/14] exec.c: Add new address_space_ld*/st* functions

[Paolo Bonzini <pbonzini@redhat.com>]

On 09/04/2015 13:49, Peter Maydell wrote:
>> > I think we do not want to expose these at all (or at least, all users
>> > should really be CPUs and hence use *_phys functions).
>> >
>> > S390 is always big-endian, and watch_mem_read/write can use the same
>> > buffer trick as subpages (and in fact should probably use memattrs as well).
>> >
>> > So, please at least add a comment that these functions are deprecated,
>> > and check if watch_mem_read/write should be handled like subpages.
> I looked at the subpages code, and it seems to me that it's the
> other way around -- the subpages code should use these new functions.
> At the moment the subpage handlers use address_space_read/write
> to pull the data into a buffer, and then use the ldl_p/stl_p functions
> to do "read data from target-CPU order buffer into host variable".
> It would be better for them to just directly be able to say "do
> a ld/st in target-CPU order into this host variable", which is
> the purpose of these new functions. Indirecting via a buffer seems
> like an ugly workaround for not having the direct operation.

Using them in subpage code is fine, but then the subpage code is in
exec.c and can use the _internal version directly (and pass
DEVICE_NATIVE_ENDIAN).  Still, usage of these outside exec.c is probably
suspicious.  It's at least worth pulling these in cpu-all.h; the whole
contents of cpu-common.h look like a sundry of functions that either are
deprecated or should be declared elsewhere.

Paolo