lkml.org 
[lkml]   [2008]   [Sep]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Driver for tightly coupled memory
From
Date
On Tue, 16 Sep 2008 22:27:41 PDT, Alessio Sangalli said:

> Well I should ask the details to the hardware engineers but it's like a
> separate channel than the one used for main memory. It is not cacheable
> either. To the CPU, it just appears to be mapped at some location on the
> addressable space. Accessing this TCM will not have any impact on main
> memory access, so bursts etc won't be interrupted; other than that, TCM
> has double the bandwidth than standard memory - but it's tiny in size,
> something like 8 to 32kB as I mentioned earlier.

Ah. So it's basically just super-fast memory that can be accessed without
going through the usual memory bus. Sounds like the cycle of reincarnation
strikes again - 30ish years ago, the DEC PDP10/20 processors implemented the
first few locations of memory in fast (for the time) chips, and then mapped
the general purpose registers onto it. A favorite trick would be to copy a
small loop into locations 0-7 and then branch to it - basically executing
from the general registers. The *real* fun started when people started doing
self-modifying code by doing arithmetic/logical operations on registers. ;)

Would it be more of a performance win to use the 8-32K to store speed-critical
code rather than a FIFO? Just another idea for what to use it for, but that
would likely require a different API...
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2008-09-17 07:43    [from the cache]
©2003-2011 Jasper Spaans