That would work, but I don't completely like it.
(a) I want s390x to select NEED_PROC_VMCORE_DEVICE_RAM instead. Staring at a
bunch of similar cases (git grep "config NEED" | grep Kconfig, git grep
"config ARCH_WANTS" | grep Kconfig), "select" is the common way to do it.
So unless there is a pretty good reason, I'll keep
NEED_PROC_VMCORE_DEVICE_RAM as is.
That's easy to satify, see below:
============simple version=====
fs/proc/Kconfig:
config NEED_PROC_VMCORE_DEVICE_RAM
def n
config PROC_VMCORE_DEVICE_RAM
def_bool y
depends on PROC_VMCORE && VIRTIO_MEM
depends on NEED_PROC_VMCORE_DEVICE_RAM
arch/s390/Kconfig:
config S390
select NEED_PROC_VMCORE_DEVICE_RAM
==============================
(b) In the context of this patch, "depends on VIRTIO_MEM" does not make
sense. We could have an intermediate:
config PROC_VMCORE_DEVICE_RAM
def_bool n
depends on PROC_VMCORE
depends on NEED_PROC_VMCORE_DEVICE_RAM
And change that with VIRTIO_MEM support in the relevant patch.
Oh, it's not comment for this patch, I made the simple version based on
the whole patchset. When I had a glance at this patch, I also took
several iterations to get it after I applied the whole patchset and
tried to understand the whole code.
I faintly remember that we try avoiding such dependencies and prefer
selecting Kconfigs instead. Just look at the SPLIT_PTE_PTLOCKS mess we still
have to clean up. But as we don't expect that many providers for now, I
don't care.
With the simple version, Kconfig learner as me can easily understand what
they are doing. If it took you a couple of iterations to make them as
you had mentioned earlier, and it took me several iterations to
understand them, I believe there must be room to improve the presented
ones in this patchset. These are only my humble opinion, and I am not
aware of virtio-mem at all, I'll leave this to you and other virtio-mem
dev to decide what should be taken. Thanks for your patience and
provided information, I learned a lot from this discussion.
===================
fs/proc/Kconfig:
config PROVIDE_PROC_VMCORE_DEVICE_RAM
def_bool n
config NEED_PROC_VMCORE_DEVICE_RAM
def_bool n
config PROC_VMCORE_DEVICE_RAM
def_bool y
depends on PROC_VMCORE
depends on NEED_PROC_VMCORE_DEVICE_RAM
depends on PROVIDE_PROC_VMCORE_DEVICE_RAM
drivers/virtio/Kconfig:
config VIRTIO_MEM
select PROVIDE_PROC_VMCORE_DEVICE_RAM if PROC_VMCORE
~~~~~~~~~~~~~~
arch/s390/Kconfig:
config S390
select NEED_PROC_VMCORE_DEVICE_RAM if PROC_VMCORE
~~~~~~~~~~~~~~
========================
One last thing I haven't got well, If PROC_VMCORE_DEVICE_RAM has had
dependency on PROC_VMCORE, can we take off the ' if PROC_VMCORE' when
select PROVIDE_PROC_VMCORE_DEVICE_RAM and NEED_PROC_VMCORE_DEVICE_RAM?