Fwd: eXpOS Design - File Manager
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Murali Krishnan
Dec 15, 2020, 10:42:54 AM12/15/20
to xos-...@googlegroups.com, Muhammed Farseeen CK, ishan ghosh, xosdev...@googlegroups.com
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From: joshwin john.jose <joshwin_...@nitc.ac.in>
Date: Tue, Dec 15, 2020 at 4:33 PM
Subject: eXpOS Design - File Manager
To: <oslabee-...@googlegroups.com>
From: joshwin john.jose <joshwin_...@nitc.ac.in>
Date: Tue, Dec 15, 2020 at 4:33 PM
Subject: eXpOS Design - File Manager
To: <oslabee-...@googlegroups.com>
The roadmap and the documentation for the File Manager module states that the third input argument for BUFFERED READ should be the 'physical memory address' of the user variable to which the word is to be read into.
Problems may arise if the process gets swapped out-in while waiting for buffer/disk inside the file manager. During such a scenario, the word might be read into a wrong address if the memory pages for the user stack had changed during swapping.
Possible fix : Third input argument to BUFFERED READER can be the user's logical address. Address translation can be done inside BUFFERED READER just before writing the word into user space.
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Akhil S
Dec 15, 2020, 11:34:37 PM12/15/20
to xos-...@googlegroups.com, Karthika Aravind, Murali Krishnan
Hi,
As far as I remember the reason for not doing this was that we had fixed in design that locked processes waiting in kernel mode will not be swapped out.
But yes, this seems like a sensible thing to do. I don't think such a change would cause any problems and it's safer to do it this way.
As far as I remember the reason for not doing this was that we had fixed in design that locked processes waiting in kernel mode will not be swapped out.
But yes, this seems like a sensible thing to do. I don't think such a change would cause any problems and it's safer to do it this way.
Akhil.
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Regards,
Akhil S
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