Disabling caching when using TFAT and other stuff
- From: alexquisi@xxxxxxxxxxxx
- Date: Fri, 10 Oct 2008 02:55:50 -0700 (PDT)
Hi all,
I am using in my WinCE 5.0 project two FMDs to divide my flash memory
in two (independent) areas, one for the hive registry and the other
for user's Storage (mounted as root). Based on this post:
http://groups.google.de/group/microsoft.public.windowsce.platbuilder/browse_thread/thread/fe97461486ba8a6c/3782c8a03712e6c8?hl=en&lnk=gst&q=two+fmd+storage+manager#3782c8a03712e6c8
I use two DLLs (but same code) for each profile. The low level access
to the flash device is controlled by a mutex.
The flags for automatically mounting, partitioning and formating are
set for both drivers. Both drivers are loaded in the 1st bootphase.
So far, it seems to be working. The problem comes when I delete ONE of
those areas (using the bootloader). After doing that, the board boots
and format BOTH areas. I don't understand why this is happening.
As I am not creating any partition in these flash areas, I tried
setting the PartitionDriver to an empty stream (in both drivers). The
formatting was faster (I guess that with the mspart library it does a
full format and without it a fast format is executed). Interesting, a
couple of month ago, this change also help me to get the formatting of
both areas independently. But now, it does not work anymore. The only
changes that I have done in the meantime were the QFE updates.
I still can't understand why these two flash areas aren't independent
from each other. Both get a different profile. For the Storage Manager
should mean that they are unrelated.
Another thing is, I am trying to disable FS caching in these profiles.
I set the EnableCache flag to zero. I don't know if this is enough(?).
I mean, I see also the FATFS_FORCE_WRITETHROUGH mask for the Flags
entry.
I tried tu used it and it makes the access to the flash by far slower
than without it. There is also the EnableWriteBack flag (which I still
don't test). I am confused. I hope that someone of you may clarify to
me those issues.
Thanks in advance for your help.
Alex
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