On 10/8/19 5:43 PM, Paul Moore wrote:
On Mon, Oct 7, 2019 at 12:35 PM Richard Haines
<richard_c_haines@xxxxxxxxxxxxxx> wrote:
On Mon, 2019-10-07 at 16:17 +0100, Richard Haines wrote:
On Mon, 2019-10-07 at 10:28 -0400, Stephen Smalley wrote:
On 10/6/19 4:51 AM, Richard Haines wrote:
Kernel 5.4 commit ca2864c6e8965c37df97f11e6f99e83e09806b1c
("binder: Add
default binder devices through binderfs when configured"),
changed
the way
the binder device is initialised and no longer automatically
generates
/dev/binder when CONFIG_ANDROID_BINDERFS=y.
This seems like a userspace ABI break, no? Same kernel config
before
and after this commit yields different behavior for
/dev/binder. I
suppose one might argue that one would only enable
CONFIG_ANDROID_BINDERFS if one wanted to use it instead of
/dev/binder
but the original commit that introduced binderfs specifically said
that
backward compatibility was preserved.
I'll need to check this further, but from what I've seen so far, is
that the /dev/binder is not available until you mount binderfs etc.
that's why Paul had the failure on 5.4 as before then is was
available
when the binder driver first initialised.
To confirm tests using kernel 5.4-rc1
Test 1 config:
CONFIG_ANDROID=y
CONFIG_ANDROID_BINDER_IPC=y
CONFIG_ANDROID_BINDERFS=y
CONFIG_ANDROID_BINDER_DEVICES="binder"
On boot no /dev/binder
To get this you have to:
mkdir /dev/binderfs 2>/dev/null
mount -t binder binder /dev/binderfs -o
context=system_u:object_r:device_t:s0 2>/dev/null
You then have devs:
binder and binder-control
Test 2 config:
CONFIG_ANDROID=y
CONFIG_ANDROID_BINDER_IPC=y
# CONFIG_ANDROID_BINDERFS is not set
CONFIG_ANDROID_BINDER_DEVICES="binder"
On boot you have /dev/binder
Disabling binderfs during build is probably not the smart thing to do
considering where the world is at with namespaces/containers, whatever
we do we should make sure the tests work with
CONFIG_ANDROID_BINDERFS=y.
Yes, I think the question is just whether we want to have the tests use
binderfs for kernel >= 5.0 (i.e. the point at which binderfs was first
introduced) or for kernel >= 5.4 (i.e. the point at which binderfs usage
became mandatory if you enable it in your config because /dev/binder is
no longer automatically created). I'm fine either way.
