Re: [PATCH 11/18] Hibernate: introduced RSA key-pair to verifysignature of snapshot

[joeyli]

æ åï2013-09-05 æ 11:31 +0100ïMatt Fleming æåï
> On Thu, 05 Sep, at 06:13:36PM, joeyli wrote:
> > This S4WakeKey is a VOLATILE variable that could not modify by
> > SetVariable() at runtime. So, it's read only even through efivars. 
> > 
> > Does it what your concern?
>  
> No, the UEFI spec probibits certain runtime functions from being
> executed concurrently on separate cpus and the spinlock used in the
> efivars code ensures that we adhere to that restriction. See table 31 in
> section 7.1 of the UEFI 2.4 spec for the list of services that are
> non-reentrant.
> 
> The problem isn't that we want to avoid simultaneous access to
> S4WakeKey, it's that we can't invoke any of the variable runtime service
> functions concurrently.
> 

I see! I will use efivar api to access EFI variable.

Thanks a lot!
Joey Lee

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