On Thu, 30 Oct, at 03:11:36PM, Mathieu Desnoyers wrote:

Hi Kirill,

This is a good point,

There are a few more aspects to consider here:

- Other architectures appear to have different guarantees, for
  instance ARM which, AFAIK, does not reset memory on soft
  reboot (well at least for my customer's boards). So I guess
  if x86 wants to be competitive, it would be good for them to
  offer a similar feature,

- Already having a subset of machines supporting this is useful,
  e.g. storing trace buffers and recovering them after a crash,

- Since we are in a world of dynamically upgradable BIOS, perhaps
  if we can show that there is value in having a BIOS option to
  specify a memory range that should not be reset on soft reboot,
  BIOS vendors might be inclined to include an option for it,

- Perhaps UEFI BIOS already have some way of specifying that a
  memory range should not be reset on soft reboot ?

We've achieved this in the past using UEFI capsules with the
EFI_CAPSULE_PERSIST_ACROSS_RESET header flag.

Unfortunately, runtime capsule support is pretty spotty, so it's not a
general solution right now.

-- 
Matt Fleming, Intel Open Source Technology Center

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