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db56946ba9
By blocking on a timeout, we yield the CPU in order to give a concurrently running sporadic process a chance to obtain ROM modules. Otherwise, such requests would be deferred until the ROM prefetcher completes its operation or in the unlikely event that the prefetcher gets preempted. Fixes #1378
156 lines
3.6 KiB
C++
156 lines
3.6 KiB
C++
/*
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* \brief ROM prefetching service
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* \author Norman Feske
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* \date 2011-01-24
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*/
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/*
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* Copyright (C) 2011-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* Genode includes */
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#include <rom_session/connection.h>
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#include <cap_session/connection.h>
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#include <root/component.h>
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#include <dataspace/client.h>
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#include <base/rpc_server.h>
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#include <base/printf.h>
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#include <base/env.h>
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#include <base/sleep.h>
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#include <os/config.h>
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#include <timer_session/connection.h>
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volatile int dummy;
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static void prefetch_dataspace(Genode::Dataspace_capability ds)
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{
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char *mapped = Genode::env()->rm_session()->attach(ds);
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Genode::size_t size = Genode::Dataspace_client(ds).size();
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/*
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* Modify global volatile 'dummy' variable to prevent the compiler
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* from removing the prefetch loop.
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*/
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enum { PREFETCH_STEP = 4096 };
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for (Genode::size_t i = 0; i < size; i += PREFETCH_STEP)
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dummy += mapped[i];
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Genode::env()->rm_session()->detach(mapped);
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}
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class Rom_session_component : public Genode::Rpc_object<Genode::Rom_session>
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{
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private:
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Genode::Rom_connection _rom;
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public:
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/**
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* Constructor
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*
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* \param filename name of the requested file
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*/
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Rom_session_component(const char *filename) : _rom(filename)
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{
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prefetch_dataspace(_rom.dataspace());
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}
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/***************************
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** ROM session interface **
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***************************/
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Genode::Rom_dataspace_capability dataspace() {
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return _rom.dataspace(); }
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void sigh(Genode::Signal_context_capability) { }
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};
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class Rom_root : public Genode::Root_component<Rom_session_component>
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{
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private:
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Rom_session_component *_create_session(const char *args)
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{
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enum { FILENAME_MAX_LEN = 128 };
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char filename[FILENAME_MAX_LEN];
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Genode::Arg_string::find_arg(args, "filename").string(filename, sizeof(filename), "");
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/* create new session for the requested file */
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return new (md_alloc()) Rom_session_component(filename);
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}
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public:
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/**
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* Constructor
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*
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* \param entrypoint entrypoint to be used for ROM sessions
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* \param md_alloc meta-data allocator used for ROM sessions
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*/
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Rom_root(Genode::Rpc_entrypoint *entrypoint,
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Genode::Allocator *md_alloc)
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:
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Genode::Root_component<Rom_session_component>(entrypoint, md_alloc)
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{ }
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};
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int main(int argc, char **argv)
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{
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using namespace Genode;
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/* connection to capability service needed to create capabilities */
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static Cap_connection cap;
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/*
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* Prefetch ROM files specified in the config
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*/
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try {
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Timer::Connection timer;
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Genode::Xml_node entry = config()->xml_node().sub_node("rom");
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for (;;) {
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enum { NAME_MAX_LEN = 64 };
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char name[NAME_MAX_LEN];
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name[0] = 0;
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entry.attribute("name").value(name, sizeof(name));
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try {
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Rom_connection rom(name);
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PINF("prefetching ROM file %s", name);
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prefetch_dataspace(rom.dataspace());
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} catch (...) {
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PERR("could not open ROM file %s", name);
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}
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/* proceed with next XML node */
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entry = entry.next("rom");
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/* yield */
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timer.msleep(1);
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}
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} catch (...) { }
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static Sliced_heap sliced_heap(env()->ram_session(),
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env()->rm_session());
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/* creation of the entrypoint and the root interface */
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enum { STACK_SIZE = 8*1024 };
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static Rpc_entrypoint ep(&cap, STACK_SIZE, "rom_pf_ep");
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static Rom_root rom_root(&ep, &sliced_heap);
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/* announce server */
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env()->parent()->announce(ep.manage(&rom_root));
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/* wait for activation through client */
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sleep_forever();
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return 0;
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};
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