Re: [ECOS] mips interrupt question

[Nick Garnett <nickg at ecoscentric dot com>]

"Andy Dyer" <adyer@righthandtech.com> writes:

> Hi all - 
> 
> I was looking through the interrupt handling stuff and the hal_vsr_table
> defined in hal/mips/arch/v2_0/src/vectors.S looks 2x too large (64
> entries vs. 32)
> to me.
> 
> The indexes into the table are generated by adding a 7 bit field in from
> the
> cause register to the base of the table.  Is there some other use of the
> extra
> 32 entries that I'm missing or a variant that uses bit 7 of the cause
> register 
> to index more entries? 


I think originally we use locations in the VSR table >32 for some
purposes similar to what we use the virtual vector table now. This is
probably a hang-over from those days. However, as the comment says,
this definition for the VSR table is never used these days. Instead it
is fixed at 0x80000100, although the space allowed there still permits
up to 64 VSRs.


-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com/     The eCos and RedBoot experts


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