On 20.12.18 18:39, Grant Likely wrote: > Instead of masking out GetVariable() when SetVariable() isn't available > during runtime services, simplify the requirements without losing the > ability to read variables by using the RuntimeServicesSupported variable > from UEFI v2.8.1 (unreleased); Mantis issue 1961. > > Peter Jones's earlier patch also specified a Capsule-on-Disk format for > updating variables that the OS could store in the ESP. I've not included > that specification in this patch as it is logically a separate feature. > It may reappear in a separate patch at a later date, or it may get > proposed for inclusion in the UEFI spec proper. > > Signed-off-by: Grant Likely <grant.lik...@arm.com> > Cc: Peter Jones <pjo...@redhat.com> > --- > source/chapter2-uefi.rst | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/source/chapter2-uefi.rst b/source/chapter2-uefi.rst > index 379f0ca..4f74d43 100644 > --- a/source/chapter2-uefi.rst > +++ b/source/chapter2-uefi.rst > @@ -201,14 +201,15 @@ variables stored on shared media. [#OPTEESupplicant]_ > > If a platform does not implement modifying non-volatile variables with > SetVariable() after ExitBootServices(), > -then it must not provide any variable operations after ExitBootServices(). > -Firmware shall return EFI_UNSUPPORTED for any call to GetVariable(), > -GetNextVariableName() and SetVariable(). > -Firmware shall not emulated non-volatile variables using volatile RAM cache. > +then firmware shall return EFI_UNSUPPORTED for any call to SetVariable(), > +and must advertise that SetVariable() isn't available during runtime services > +via the "RuntimeServicesSupported" variable as defined in UEFI version 2.8.1. > +EFI applications can read RuntimeServicesSupported to determine if calls
UEFI? > +to SetVariable() need to be performed before calling ExitBootServices(). I think this bit needs a bit more explanation. Something along the lines "If an OS needs to modify UEFI variables, it can only reliably do so before ExitBootServices()"? > > -.. note:: The behaviour when SetVariable() is not supported during runtime > - services is still under discussion and subject to change. > - Do not make any firmware implementation decisions based on this text yet. > +Even when SetVariable() is not supported during runtime services, firmware > +should cache variable names and values in EfiRuntimeServicesData memory so > +that GetVariable() and GetNextVeriableName() can behave as specified. Please note that this will require work in U-Boot and is currently not implemented ;). Alex _______________________________________________ boot-architecture mailing list boot-architecture@lists.linaro.org https://lists.linaro.org/mailman/listinfo/boot-architecture
