* fail to disable MMU on ppc 8241
@ 2004-04-19 3:55 llee
2004-04-19 5:20 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 3+ messages in thread
From: llee @ 2004-04-19 3:55 UTC (permalink / raw)
To: linuxppc-dev
Hi, there,
I boot linux (2.6.3) on my ppc 8241 through vxworks bootloader. I'd got
a port (on address 0x70020006) to constrol three LEDs, so I could know
where the kernel going. But after the disable_mmu is called, I lost
control to the LEDs, Any suggestion on this? As I know, vxworks use a
one-to-one mapping MMU setup, I should must constrol the LEDs through
the same address.
Thanks for any suggestion.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: fail to disable MMU on ppc 8241
2004-04-19 3:55 fail to disable MMU on ppc 8241 llee
@ 2004-04-19 5:20 ` Benjamin Herrenschmidt
2004-04-20 1:45 ` llee
0 siblings, 1 reply; 3+ messages in thread
From: Benjamin Herrenschmidt @ 2004-04-19 5:20 UTC (permalink / raw)
To: llee; +Cc: linuxppc-dev list
On Mon, 2004-04-19 at 13:55, llee wrote:
> Hi, there,
> I boot linux (2.6.3) on my ppc 8241 through vxworks bootloader. I'd got
> a port (on address 0x70020006) to constrol three LEDs, so I could know
> where the kernel going. But after the disable_mmu is called, I lost
> control to the LEDs, Any suggestion on this? As I know, vxworks use a
> one-to-one mapping MMU setup, I should must constrol the LEDs through
> the same address.
With mmu off, I suspect the 8241 acts as if the entire address space
was cacheable, which is a BAD THING for IOs typically.
Ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: fail to disable MMU on ppc 8241
2004-04-19 5:20 ` Benjamin Herrenschmidt
@ 2004-04-20 1:45 ` llee
0 siblings, 0 replies; 3+ messages in thread
From: llee @ 2004-04-20 1:45 UTC (permalink / raw)
To: Benjamin Herrenschmidt; +Cc: linuxppc-dev list
Benjamin Herrenschmidt wrote:
>On Mon, 2004-04-19 at 13:55, llee wrote:
>
>
>>Hi, there,
>>I boot linux (2.6.3) on my ppc 8241 through vxworks bootloader. I'd got
>>a port (on address 0x70020006) to constrol three LEDs, so I could know
>>where the kernel going. But after the disable_mmu is called, I lost
>>control to the LEDs, Any suggestion on this? As I know, vxworks use a
>>one-to-one mapping MMU setup, I should must constrol the LEDs through
>>the same address.
>>
>>
>
>With mmu off, I suspect the 8241 acts as if the entire address space
>was cacheable, which is a BAD THING for IOs typically.
>
>Ben.
>
>
>
>
>
>
Thanks Ben, It works when I disable DATA CACHE!
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
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2004-04-19 5:20 ` Benjamin Herrenschmidt
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