Re: [edk2-devel] [PATCH resend] MdeModulePkg/EsrtDxe: allocate ESRT table from RtServicesData memory

["Michael D Kinney" <michael.d.kinney@intel.com>]

Ard,

Let's see if we can remove the ESRT access from those
paths.  That would be the better fix.

Thanks,

Mike

> -----Original Message-----
> From: devel@edk2.groups.io
> [mailto:devel@edk2.groups.io] On Behalf Of Ard
> Biesheuvel
> Sent: Friday, April 19, 2019 11:11 AM
> To: Kinney, Michael D <michael.d.kinney@intel.com>
> Cc: devel@edk2.groups.io; ming.huang@linaro.org; Wu,
> Hao A <hao.a.wu@intel.com>; Wang, Jian J
> <jian.j.wang@intel.com>
> Subject: Re: [edk2-devel] [PATCH resend]
> MdeModulePkg/EsrtDxe: allocate ESRT table from
> RtServicesData memory
> 
> On Fri, 19 Apr 2019 at 20:08, Kinney, Michael D
> <michael.d.kinney@intel.com> wrote:
> >
> > Ard,
> >
> > Where is the use of ESRT at runtime?
> >
> 
> DxeCapsuleLibFmp is invoked at runtime by the
> UpdateCapsule() and
> QueryCapsuleCapabilities() code.
> 
> The Canonical FWTS crashes on this runtime service on
> some ARM and x86
> systems due to this issue, hence the patch.
> 
> 
> > The SetVa conversion of the ESRT table may be an old
> artifact
> > that we should consider removing.
> >
> 
> No, it is definitely live code.
> 
> 
> >
> > > -----Original Message-----
> > > From: devel@edk2.groups.io
> > > [mailto:devel@edk2.groups.io] On Behalf Of Ard
> > > Biesheuvel
> > > Sent: Friday, April 19, 2019 10:54 AM
> > > To: edk2-devel-groups-io <devel@edk2.groups.io>;
> > > Kinney, Michael D <michael.d.kinney@intel.com>
> > > Cc: ming.huang@linaro.org; Wu, Hao A
> > > <hao.a.wu@intel.com>; Wang, Jian J
> > > <jian.j.wang@intel.com>
> > > Subject: Re: [edk2-devel] [PATCH resend]
> > > MdeModulePkg/EsrtDxe: allocate ESRT table from
> > > RtServicesData memory
> > >
> > > On Fri, 19 Apr 2019 at 19:42, Ard Biesheuvel
> > > <ard.biesheuvel@linaro.org> wrote:
> > > >
> > > > On Fri, 19 Apr 2019 at 19:36, Michael D Kinney
> > > > <michael.d.kinney@intel.com> wrote:
> > > > >
> > > > > Hi Ard,
> > > > >
> > > > > The UEFI Specification Section 23.3 says:
> > > > >
> > > > >         "The ESRT shall be stored in memory of
> type
> > > EfiBootServicesData."
> > > > >
> > > > > If an RT driver needs ESRT info after
> > > ExitBootServices(), then the
> > > > > RT driver should collect that information
> before
> > > ExitBootServices().
> > > > >
> > > >
> > > > But that means that before EBS(), we will have to
> > > make a copy of the
> > > > ESRT into runtime services data, and we will end
> up
> > > using twice as
> > > > much memory - one copy in boot services data for
> the
> > > OS, and one copy
> > > > in runtime services data for the firmware itself.
> I
> > > understand the
> > > > reasoning behind preferring boot over runtime, so
> > > that the OS is not
> > > > burdened with it if it does not care. But it this
> > > case, the RT
> > > > services data will be allocated regardless, and
> so we
> > > end up using
> > > > less memory if we expose that same copy to the
> OS.
> > > >
> > >
> > > Actually, DxeCapsuleLibVirtualAddressChangeEvent()
> in
> > > DxeCapsuleLibFmp
> > > updates the ESRT pointer to virtual, so this code
> is
> > > clearly based on
> > > the assumption that the ESRT resides in memory that
> is
> > > covered by a
> > > runtime VA mapping.
> > >
> > > Could we instead clarify the UEFI spec to something
> > > like
> > >
> > > "The ESRT shall be stored in memory of type
> > > EfiBootServicesData unless
> > > the runtime services implementations themselves
> need to
> > > access it at
> > > OS runtime, in which case it may be stored in
> > > EfiRuntimeServicesData."
> > >
> > >
> >
> 
>