On Mon, Jun 05, 2000 at 03:55:51PM -0400, Rabeeh Khoury wrote:
> I'v added a code to debug the TLB misses in my kernel (2.2)
> I'm running QED RM5271 in big mips mode ; I'v added the following code :
> 8004de54: 3c010300 lui $at,0x300
> 8004de58: ac200000 sw $zero,0($at)
> which simply writes zero to virtual address 0x03000000, this code is
> invoked in kernel mode in kernel space and tries to write to user space.
> after this I get a TLB exception with an error TLBL (TLB miss because of
> load or instruction fetch) !!!!!!!!!!!!!!!
> instead of TLBS.
Do you observe this tlbl exception code in or via the general exception
vector handler at 0x80000180? If so you're taking a exception within
the other exception handler at 0x80000000. There are special rules for
this nested exception that is the EPC and BadVAddr registers will keep
their old values.
> the CP0_STATUS = 00800008
> p.s. I have also strange values in the BADVADDR and CONEXT.
What is CONEXT?
> can any one speculate what is the problem ?
> do I need to do any thing special to access user space in kernel mode ?
There is nothing obviously missing.