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dev: Add post-fork handling for disk images

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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>
This commit is contained in:
Andreas Sandberg 2015-11-26 10:11:52 +00:00
parent 738d71f6a9
commit 6de52699bb
2 changed files with 31 additions and 2 deletions
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29
src/dev/storage/disk_image.cc
View file

@ -64,6 +64,17 @@ RawDiskImage::RawDiskImage(const Params* p)
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)
{
@ -197,6 +208,16 @@ 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)
{
@ -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

4
src/dev/storage/disk_image.hh
View file

@ -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;