[U-Boot] [PATCH 1/3] PPC 85xx: Detect e500v2 / e500mc during runtime

[Kumar Gala]

On Mar 6, 2014, at 9:50 AM, Scott Wood <scottwood at freescale.com> wrote:

> On Thu, 2014-03-06 at 09:48 -0600, Kumar Gala wrote:
>> On Jan 23, 2014, at 6:11 AM, Alexander Graf <agraf at suse.de> wrote:
>> 
>>> 
>>> On 21.01.2014, at 03:25, Scott Wood <scottwood at freescale.com> wrote:
>>> 
>>>> On Sun, 2014-01-19 at 16:19 +0100, Alexander Graf wrote:
>>>>> With the qemu-ppce500 machine type we can run the same board with
>>>>> either an e500v2 or an e500mc core plugged in.
>>>>> 
>>>>> This means that the IVOR setup can't be based on compile time decisions,
>>>>> so instead we have to do a runtime check which CPU generation we're
>>>>> running on.
>>>> 
>>>> Is this really the only place where you ran into this?
>>> 
>>> Yup. At least the only place where the difference actually matters for a VM.
>>> 
>>>> Also consider that you'll be adding extra size, and some of our 85xx
>>>> targets are pretty close to the limit as is (though at least this code
>>>> isn't used in SPLs).
>>>> 
>>>> I guess nobody ever bothered to set IVORs for e6500-specific exceptions.
>>>> 
>>>> For that matter, I don't see why we need this code at all.  These aren't
>>>> the addresses that U-Boot keeps its exception vectors at; it's setting
>>>> them up for the OS, apparently trying to imitate some other type of
>>>> book3e chip that has fixed ivors.  Apparently U-Boot has done this only
>>>> since 2009 (commit 26f4cdba6b51deab4ec99d60be381244068ef950), so it's
>>>> not even something that an OS could depend on (and certainly Linux
>>>> doesn't).  So I don't see the point.
>>> 
>>> Kumar, do you remember why you put this in? Was it only for prototyping purposes?
>>> 
>>> I certainly wouldn't mind removing the whole thing altogether.
>>> 
>>> 
>>> Alex
>> 
>> 
>> I feel like we did have some support for timer & external interrupts in u-boot.  Its been a while since I looked.
> 
> This has nothing to do with U-Boot's own exception handlers -- this is
> what U-Boot is currently doing just prior to entering the OS.
> 
> -Scott
> 

Oh, right.  Did e6500 move to fixed IVORs?  If not this can probably be removed as I doubt there will be a new core from FSL that would require this.  It was meant as a transition for any OS that cared (if my memory serves me).

- k