On 9 April 2015 at 13:00, Paolo Bonzini <pbonz...@redhat.com> wrote: > > > 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.
I use them (later in the series) in target-arm/ as well, when I want a CPU-target-endian access which lets me specify memory attributes. > 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. They need to be in memory.h because cpu-all.h doesn't have all the typedefs. Also, memory.h seems to me clearly the best place, since it's where we declare the MemoryRegion and AddressSpace related functions. It's certainly true that using target-cpu-endian functions in a device is somewhat suspicious, but that's generally true of all those functions, not just these new address_space_* ones. So I think I'm happy to add a comment that the functions are deprecated for use outside target-*/, but I think they are still necessary. -- PMM
