Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless

From	Bryan O'Donoghue <pure.logic@nexus-software.ie>
Newsgroups	linux.kernel
Subject	Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless
Date	2016-05-06 03:40 +0200
Message-ID	<rvCUi-3pX-1@gated-at.bofh.it> (permalink)
References	(3 earlier) <rv1rI-1lo-1@gated-at.bofh.it> <rv3tw-33X-25@gated-at.bofh.it> <rv46e-3HL-13@gated-at.bofh.it> <rv682-5L8-11@gated-at.bofh.it> <rvsrU-1xL-1@gated-at.bofh.it>
Organization	Nexus Software

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On Thu, 2016-05-05 at 14:27 +0000, Kweh, Hock Leong wrote:
> > -----Original Message-----
> > From: Matt Fleming [mailto:matt@codeblueprint.co.uk]
> > Sent: Wednesday, May 04, 2016 10:36 PM
> > To: Kweh, Hock Leong; Bryan O'Donoghue
> > Cc: linux-efi@vger.kernel.org; linux-kernel@vger.kernel.org; Ard
> > Biesheuvel;
> > joeyli; Borislav Petkov
> > Subject: Re: [PATCH] efi/capsule: Make efi_capsule_pending()
> > lockless
> > 
> > On Wed, 04 May, at 02:20:42PM, Borislav Petkov wrote:
> > > 
> > > Blergh.
> > 
> > Wilson, Bryan, what kind of rollback support does the Intel Quark
> > have if its
> > firmware update is interrupted?
> > 
> > The interruption could be for a number of reasons including power
> > loss, or
> > the example in this case, rebooting due to panic().
> 
> If not mistaken, the EFI firmware will not update a partially
> uploaded binary due to checksum error.
> User is required to re-update the efi capsule again on the next boot
> up.
> 

If the checksum fails then you're fine since you won't update flash.

OTOH if you pull the plug we actually have a backup image - so even a
partially flashed update shouldn't brick the system.

How well that actually works i.e. is it tested in anger ? Meh - YMMV
there fore sure.

---
bod

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[PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-01 00:20 +0200
  Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Borislav Petkov <bp@alien8.de> - 2016-05-03 11:10 +0200
    Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-03 16:20 +0200
      Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Borislav Petkov <bp@alien8.de> - 2016-05-04 11:40 +0200
        Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-04 13:50 +0200
          Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Borislav Petkov <bp@alien8.de> - 2016-05-04 14:30 +0200
            Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-04 15:40 +0200
            Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-04 16:40 +0200
              RE: [PATCH] efi/capsule: Make efi_capsule_pending() lockless "Kweh, Hock Leong" <hock.leong.kweh@intel.com> - 2016-05-05 16:30 +0200
                Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-05 16:40 +0200
                Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-05-05 17:00 +0200
                Re: [PATCH] efi/capsule: Make efi_capsule_pending() lockless Bryan O'Donoghue <pure.logic@nexus-software.ie> - 2016-05-06 03:40 +0200

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