Re: [Qemu-devel] [PATCH] memory: check write/read_with_attrs in memory dispatch

[Peter Maydell <peter.maydell@linaro.org>]

On 13 November 2018 at 01:42, Li Qiang <liq3ea@gmail.com> wrote:
> This can avoid the NULL-deref if the rm doesn't has a
> read/write nor write/read_with_attrs callback.
>
> Signed-off-by: Li Qiang <liq3ea@gmail.com>
> ---
>  memory.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)

Alternative approach -- assert that every MemoryRegionOps has
pointers to callbacks in it, when it is registered in memory_region_init_io()
and memory_region_init_rom_device_nomigrate().

I don't have a strong opinion on which is better, but I guess
I slightly favour requiring devices to be specific about what
their read/write behaviour is.

Do we have many devices that legitimately only want to implement
one of read and write, not both ?

thanks
-- PMM