Thread (4 messages) 4 messages, 3 authors, 2011-06-29

[RFC 7/8] drivers: introduce rpmsg, a remote-processor messaging bus

From: arnd@arndb.de (Arnd Bergmann)
Date: 2011-06-29 11:59:31
Also in: linux-omap, lkml

Possibly related (same subject, not in this thread)

On Wednesday 29 June 2011, Ohad Ben-Cohen wrote:
On Wed, Jun 29, 2011 at 2:44 AM, Randy Dunlap [off-list ref] wrote:
quoted
quoted
+hardware accelerators, and therefore are often used to offload cpu-intensive
prefer:                                                           CPU-
throughout.
Isn't that changing the meaning a bit ? Let's stick with the original
version, I think it's more clear.
I think you misunderstood Randy, he meant you should do 's/cpu/CPU/' globally,
which does not change the meaning.
quoted
quoted
+system's physical memory and/or other sensitive hardware resources (e.g. on
+OMAP4, remote cores (/hardware accelerators) may have direct access to the
+physical memory, gpio banks, dma controllers, i2c bus, gptimers, mailbox
+devices, hwspinlocks, etc..). Moreover, those remote processors might be
+running RTOS where every task can access the entire memory/devices exposed
+to the processor. To minimize the risks of rogue (/buggy) userland code
What is with the leading / here and above (/hardware) and below?
/ here means "or". You can read the sentence twice, either without the
(/ ..) options or with them, and then you get two (different)
examples.

Any idea how to make it more readable ? I prefer not to drop the
second example, as it's adding information.
The easiest way would be to replace it with 'or', as in

... remote cores (or hardware accelerators) may have ...

I would also suggest you drop the parentheses, especially in the first
case where you have two levels of them:

system's physical memory and/or other sensitive hardware resources, e.g. on
OMAP4, remote cores and hardware accelerators may have direct access to the
specific hardware blocks such as physical memory, gpio banks or dma
controllers.
Moreover, those remote processors might be...
quoted
quoted
+if RPMSG
+
+# OK, it's a little counter-intuitive to do this, but it puts it neatly under
+# the rpmsg menu (and it's the approach preferred by the virtio folks).
+
+source "drivers/virtio/Kconfig"
It seems odd to have that Kconfig file sourced in multiple places.
Are the kconfig tools happy with that?
They are, probably because these places are mutually exclusive today:

$ git grep "drivers/virtio/Kconfig"
arch/ia64/kvm/Kconfig:source drivers/virtio/Kconfig
arch/mips/Kconfig:source drivers/virtio/Kconfig
arch/powerpc/kvm/Kconfig:source drivers/virtio/Kconfig
arch/s390/kvm/Kconfig:source drivers/virtio/Kconfig
arch/sh/Kconfig:source drivers/virtio/Kconfig
arch/tile/kvm/Kconfig:source drivers/virtio/Kconfig
arch/x86/kvm/Kconfig:source drivers/virtio/Kconfig

Now that we start using virtio for inter-processor communications,
too, we might soon bump into a situation where virtio will be sourced
twice.

Probably the solution is to move 'source "drivers/virtio/Kconfig"'
into drivers/Kconfig, and remove all other instances.
I think changing that would be good. However, you need to at least
restructure the contents, or they will show up in the main driver menu.

	Arnd
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