Hi All,
I am using remap_page_range to map a memory region
to user space. (This is a device memory mapped in
to kernel space by ioremap_nocache.)
I am setting the page protection flags as
_PAGE_PCD | _PAGE_PWT to disable caching as
specified in the documentation.
But when I try to read these device registers in the
user space it shows different values from
those of driver. I declared the necessary
members as volatile. But it still does not help.
When I try to read the register twice I seem to be
getting the correct value.
Like,
/* ulBWStatus is defined as volatile. */
status = pRpRegs->ulBStatus;
status = pRpRegs->ulBStatus;
This gives me the updated values. Could you
just help me if I am missing anything here.
D0 I need to insert a memory barrier in the user
space
before accessing these registers ?
If I do so then it looks like giving correct values
too.
Could somebody help to understand on what is
happening here.
Thanks in advance.
best regards,
--thomas
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This archive was generated by hypermail 2b29 : Sun Mar 23 2003 - 22:00:30 EST