This patch improves the accounting for the backing store of
session-state meta data. Originally, the session state used to be
allocated by a child-local heap partition fed from the child's RAM
session. However, whereas this approach was somehow practical from a
runtime's (parent's) point of view, the child component could not count
on the quota in its own RAM session. I.e., if the Child::heap grew at
the parent side, the child's RAM session would magically diminish. This
caused two problems. First, it violates assumptions of components like
init that carefully manage their RAM resources (and giving most of them
away their children). Second, if a child transfers most of its RAM
session quota to another RAM session (like init does), the child's RAM
session may actually not allow the parent's heap to grow, which is a
very difficult error condition to deal with.
In the new version, there is no Child::heap anymore. Instead, session
states are allocated from the runtime's RAM session. In order to let
children pay for these costs, the parent withdraws the local session
costs from the session quota donated from the child when the child
initiates a new session. Hence, in principle, all components on the
route of the session request take a small bite from the session quota to
pay for their local book keeping
Consequently, the session quota that ends up at the server may become
depleted more or less, depending on the route. In the case where the
remaining quota is insufficient for the server, the server responds with
'QUOTA_EXCEEDED'. Since this behavior must generally be expected, this
patch equips the client-side 'Env::session' implementation with the
ability to re-issue session requests with successively growing quota
donations.
For several of core's services (ROM, IO_MEM, IRQ), the default session
quota has now increased by 2 KiB, which should suffice for session
requests to up to 3 hops as is the common case for most run scripts. For
longer routes, the retry mechanism as described above comes into effect.
For the time being, we give a warning whenever the server-side quota
check triggers the retry mechanism. The warning may eventually be
removed at a later stage.
This method is a hook to enable a runtime to respond to state changes.
In particular, in init this hook is used to trigger the generation of a
new state report, if configured.
Furthermore, the patch introduces the 'generate_client_side_info' and
'generate_server_side_info' methods to the 'Session_state', which
generates an XML representation of the session states to appear in
reports produced by init.
Issue #2246
The new return value of 'resolve_session_request' allows the child
policy to define the label used as the policy selector at the server.
Because this patch introduces the distinction of the child-provided
label from the label as presented to the server along with the session
request, the latter is now handled as a dedicated 'Session_state'
argument.
Issue #2248
This commit addresses the situation where an environment session
outlives the session-providing service. In this case, the env session
got already invaidated at the destruction time of the server. However,
the underlying session-state structure continues to exist until the
client is destructed. During the eventual destruction of such a dangling
environment session, we have to be careful not to interact with the
no-longer existing service.
Ref #2197
This patch changes the child-construction procedure to allow the routing
of environment sessions to arbitrary servers, not only to the parent.
In particular, it restores the ability to route the LOG session of the
child to a LOG service provided by a child of init. In principle, it
becomes possible to also route the immediate child's PD, CPU, and RAM
environment sessions in arbitrary ways, which simplifies scenarios that
intercept those sessions, e.g., the CPU sampler.
Note that the latter ability should be used with great caution because
init needs to interact with these sessions to create/destruct the child.
Normally, the sessions are provided by the parent. So init is safe at
all times. If they are routed to a child however, init will naturally
become dependent on this particular child. For the LOG session, this is
actually not a problem because even though the parent creates the LOG
session as part of the child's environment, it never interacts with the
session directly.
Fixes#2197
This patch unconditionally applies the labeling of sessions and thereby
removes the most common use case of 'Child_policy::filter_session_args'.
Furthermore, the patch removes an ambiguity of the session labels of
sessions created by the parent of behalf of its child, e.g., the PD
session created as part of 'Child' now has the label "<child-name>"
whereas an unlabeled PD-session request originating from the child
has the label "<child-name> -> ". This way, the routing-policy of
'Child_policy::resolve_session_request' can differentiate both cases.
As a consequence, the stricter labeling must now be considered wherever
a precise label was specified as a key for a session route or a server-
side policy selection. The simplest way to adapt those cases is to use a
'label_prefix' instead of the 'label' attribute. Alternatively, the
'label' attribute may used by appending " -> " (note the whitespace).
Fixes#2171
This is a redesign of the root and parent interfaces to eliminate
blocking RPC calls.
- New session representation at the parent (base/session_state.h)
- base-internal root proxy mechanism as migration path
- Redesign of base/service.h
- Removes ancient 'Connection::KEEP_OPEN' feature
- Interface change of 'Child', 'Child_policy', 'Slave', 'Slave_policy'
- New 'Slave::Connection'
- Changed child-construction procedure to be compatible with the
non-blocking parent interface and to be easier to use
- The child's initial LOG session, its binary ROM session, and the
linker ROM session have become part of the child's envirenment.
- Session upgrading must now be performed via 'env.upgrade' instead
of performing a sole RPC call the parent. To make RAM upgrades
easier, the 'Connection' provides a new 'upgrade_ram' method.
Issue #2120
Besides adapting the components to the use of base/log.h, the patch
cleans up a few base headers, i.e., it removes unused includes from
root/component.h, specifically base/heap.h and
ram_session/ram_session.h. Hence, components that relied on the implicit
inclusion of those headers have to manually include those headers now.
While adjusting the log messages, I repeatedly stumbled over the problem
that printing char * arguments is ambiguous. It is unclear whether to
print the argument as pointer or null-terminated string. To overcome
this problem, the patch introduces a new type 'Cstring' that allows the
caller to express that the argument should be handled as null-terminated
string. As a nice side effect, with this type in place, the optional len
argument of the 'String' class could be removed. Instead of supplying a
pair of (char const *, size_t), the constructor accepts a 'Cstring'.
This, in turn, clears the way let the 'String' constructor use the new
output mechanism to assemble a string from multiple arguments (and
thereby getting rid of snprintf within Genode in the near future).
To enforce the explicit resolution of the char * ambiguity, the 'char *'
overload of the 'print' function is marked as deleted.
Issue #1987
This patch moves the thread operations from the 'Cpu_session'
to the 'Cpu_thread' interface.
A noteworthy semantic change is the meaning of the former
'exception_handler' function, which used to define both, the default
exception handler or a thread-specific signal handler. Now, the
'Cpu_session::exception_sigh' function defines the CPU-session-wide
default handler whereas the 'Cpu_thread::exception_sigh' function
defines the thread-specific one.
To retain the ability to create 'Child' objects without invoking a
capability, the child's initial thread must be created outside the
'Child::Process'. It is now represented by the 'Child::Initial_thread',
which is passed as argument to the 'Child' constructor.
Fixes#1939
This patch makes the former 'Process' class private to the 'Child'
class and changes the constructor of the 'Child' in a way that
principally enables the implementation of single-threaded runtime
environments that virtualize the CPU, PD, and RAM services. The
new interfaces has become free from side effects. I.e., instead
of implicitly using Genode::env()->rm_session(), it takes the reference
to the local region map as argument. Also, the handling of the dynamic
linker via global variables is gone. Now, the linker binary must be
provided as constructor argument.
Fixes#1949
This patch replaces the former 'Pd_session::bind_thread' function by a
PD-capability argument of the 'Cpu_session::create_thread' function, and
removes the ancient thread-start protocol via 'Rm_session::add_client' and
'Cpu_session::set_pager'. Threads are now bound to PDs at their creation
time and implicitly paged according to the address space of the PD.
Note the API change:
This patch changes the signature of the 'Child' and 'Process' constructors.
There is a new 'address_space' argument, which represents the region map
representing the child's address space. It is supplied separately to the
PD session capability (which principally can be invoked to obtain the
PD's address space) to allow the population of the address space
without relying on an 'Pd_session::address_space' RPC call.
Furthermore, a new (optional) env_pd argument allows the explicit
overriding of the PD capability handed out to the child as part of its
environment. It can be used to intercept the interaction of the child
with its PD session at core. This is used by Noux.
Issue #1938
This patch integrates three region maps into each PD session to
reduce the session overhead and to simplify the PD creation procedure.
Please refer to the issue cited below for an elaborative discussion.
Note the API change:
With this patch, the semantics of core's RM service have changed. Now,
the service is merely a tool for creating and destroying managed
dataspaces, which are rarely needed. Regular components no longer need a
RM session. For this reason, the corresponding argument for the
'Process' and 'Child' constructors has been removed.
The former interface of the 'Rm_session' is not named 'Region_map'. As a
minor refinement, the 'Fault_type' enum values are now part of the
'Region_map::State' struct.
Issue #1938
Instead of returning pointers to locked objects via a lookup function,
the new object pool implementation restricts object access to
functors resp. lambda expressions that are applied to the objects
within the pool itself.
Fix#884Fix#1658
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
