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authorAndreas Sandberg <andreas@sandberg.pp.se>2015-11-26 10:11:52 +0000
committerAndreas Sandberg <andreas@sandberg.pp.se>2015-11-26 10:11:52 +0000
commit6de52699bb10ec445e45400b419bb61122a68162 (patch)
tree5b9fef2a697556e4b9cca062bcd50fa5c0f440aa /src
parent738d71f6a93e2da9ef5bb1490f2b94f9541735e3 (diff)
downloadgem5-6de52699bb10ec445e45400b419bb61122a68162.tar.xz
dev: Add post-fork handling for disk images
This changeset adds support for notifying the disk images that the simulator has been forked. We need to disable the saving of the CoW disk image from the child process, and we need to make sure that systems which use a raw disk image are not allowed to fork to avoid two or more gem5 processes writing to the same disk image. Signed-off-by: Andreas Sandberg <andreas@sandberg.pp.se> [sascha.bischoff@arm.com: Rebased patches onto a newer gem5 version] Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com> Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Diffstat (limited to 'src')
-rw-r--r--src/dev/storage/disk_image.cc29
-rw-r--r--src/dev/storage/disk_image.hh4
2 files changed, 31 insertions, 2 deletions
diff --git a/src/dev/storage/disk_image.cc b/src/dev/storage/disk_image.cc
index 24688f55a..e7fda40a2 100644
--- a/src/dev/storage/disk_image.cc
+++ b/src/dev/storage/disk_image.cc
@@ -65,6 +65,17 @@ RawDiskImage::~RawDiskImage()
{ close(); }
void
+RawDiskImage::notifyFork()
+{
+ if (initialized && !readonly)
+ panic("Attempting to fork system with read-write raw disk image.");
+
+ const Params *p(dynamic_cast<const Params *>(params()));
+ close();
+ open(p->image_file, p->read_only);
+}
+
+void
RawDiskImage::open(const string &filename, bool rd_only)
{
if (!filename.empty()) {
@@ -198,6 +209,16 @@ CowDiskImage::~CowDiskImage()
}
void
+CowDiskImage::notifyFork()
+{
+ if (!dynamic_cast<const Params *>(params())->read_only &&
+ !filename.empty()) {
+ inform("Disabling saving of COW image in forked child process.\n");
+ filename = "";
+ }
+}
+
+void
SafeRead(ifstream &stream, void *data, int count)
{
stream.read((char *)data, count);
@@ -311,8 +332,12 @@ SafeWriteSwap(ofstream &stream, const T &data)
void
CowDiskImage::save() const
{
- save(filename);
-}
+ // filename will be set to the empty string to disable saving of
+ // the COW image in a forked child process. Save will still be
+ // called because there is no easy way to unregister the exit
+ // callback.
+ if (!filename.empty())
+ save(filename);}
void
CowDiskImage::save(const string &file) const
diff --git a/src/dev/storage/disk_image.hh b/src/dev/storage/disk_image.hh
index 43e6adf5e..2a59dc0c3 100644
--- a/src/dev/storage/disk_image.hh
+++ b/src/dev/storage/disk_image.hh
@@ -82,6 +82,8 @@ class RawDiskImage : public DiskImage
RawDiskImage(const Params *p);
~RawDiskImage();
+ void notifyFork() override;
+
void close();
void open(const std::string &filename, bool rd_only = false);
@@ -123,6 +125,8 @@ class CowDiskImage : public DiskImage
CowDiskImage(const Params *p);
~CowDiskImage();
+ void notifyFork() override;
+
void initSectorTable(int hash_size);
bool open(const std::string &file);
void save() const;