Subject: question regarding different p_addr_t
To: None <>
From: Garrett D'Amore <>
List: tech-kern
Date: 10/25/2005 13:06:24

I've posted this to mips and evbmips, but not gotten much response.

For reasons I won't go into here, I need to increase the size of paddr_t 
on the Alchemy processors, which are currently covered by the evbmips port.

The question is whether changing this size creates the need to for a new 

It seems like this data type (paddr_t) is used in few different places 
(e.g. struct mbuf).

Changing the size to 64-bits leaves a working kernel, and -- as far as I 
can tell -- the evbmips userland built with it set for 32-bit also seems 
to work.

What I'm not confident is kernel memory grovelers and debuggers.

Is there a reason to believe that a kernel with this type at 64-bits 
should not be used with a userland compiled for it at 32-bits?

Interestingly enough, it appears that there is at least one case where a 
64-bit MIPS kernel is used with a 32-bit MIPS userland.  I'm guessing 
that this is an indication that type mismatches between userland and the 
kernel are OK as long as they aren't in structures exposed to userland 
(e.g. ioctls).

Any thoughts or advice on this matter is appreciated.  Thanks!

    -- Garrett