Re: [RFC PATCH v4] ARM hibernation/suspend-to-disk support

On 6/9/2011 10:37 PM, Frank Hofmann wrote:

On Thu, 9 Jun 2011, Santosh Shilimkar wrote:

quoted

On 6/9/2011 9:56 PM, Frank Hofmann wrote:

quoted

[ ... ]

quoted

quoted

a) What reasons if any are there why cpu_{v7_do_}suspend/resume are not
ok to use (on OMAP) for snapshotting core state, for the purpose of
hibernation ?
If there are any such issues, then how could they be addresssed ?

Part of the answer is what Russell described. We think it's doable,
but it needs some work. First and fore most is this code should
be able to be executed from DDR. It's not the case today.

Ah, I gather that's the _real_ critical point, i.e.

_omap_sram_idle = omap_sram_push(omap34xx_cpu_suspend,
omap34xx_cpu_suspend_sz);

relies on this to be completely consecutive in mem, and relocatable,
i.e. calling _outside_ that area isn't possible ?

I.e. unless a way can be found to _embed_ cpu_suspend/resume here, it's
pretty hard to use ?

Would it be possible / acceptable to have it be relocatable code, and
put it into a common .section ?

Surely acceptable :)
But other points about callback are also important o.w
you will use MMU with wrong CP15 configurations after
one sleep transition.