Re: [PATCH 4/5] arm64: Verify CPU errata work arounds on hotplugged CPU

From: Suzuki K Poulose
Date: Mon Apr 18 2016 - 09:41:28 EST

On 15/04/16 15:12, Will Deacon wrote:
On Fri, Apr 15, 2016 at 03:10:27PM +0100, Suzuki K Poulose wrote:
On 14/04/16 18:49, Suzuki K Poulose wrote:
On 14/04/16 18:39, Will Deacon wrote:
On Wed, Apr 06, 2016 at 12:24:13PM +0100, Suzuki K Poulose wrote:
CPU Errata work arounds are detected and applied to the
kernel code at boot time and the data is then freed up.
If a new hotplugged CPU requires a work around which
was not applied at boot time, there is nothing we can
do but simply fail the booting.

Hmm, wouldn't it be better not to free the alternative text for errata
workarounds instead?

We could. I don't have a strong opinion. If there are no objections, I could
adopt it.

The alternatives have been merged to .init by :

commit 9aa4ec1571da6236 ("arm64: mm: fold alternatives into .init")


Do you have any concerns on applying alternatives for CPUs turned online later ?
We have to revert the patch above to get going

Well, note that I'm only suggesting that we keep the alternatives for
CPU errata workarounds.

So to confirmt, do you mean for now we could do :

- Not release the alternatives for errata work arounds.
- And retain the check for new erratas, failing the CPUs.

And in a follow up series,

- Add support for applying errata work arounds later, as we find
a new CPU which requires it
- and remove the constraint above ?