Re: correct way to reserve memory from PrePi?

["Gao, Liming" <liming.gao@intel.com>]

Michael:
  I agree this is an issue that DxeCore doesn't consider the allocated memory range when it allocates the first memory range. Could you submit it in bugzilla with the detail usage model? Then, we can continue to investgate how to resolve it.  

Thanks
Liming
> -----Original Message-----
> From: Michael Zimmermann [mailto:sigmaepsilon92@gmail.com]
> Sent: Thursday, December 15, 2016 1:02 PM
> To: Gao, Liming <liming.gao@intel.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; edk2-devel@lists.01.org
> <edk2-devel@ml01.01.org>; Zeng, Star <star.zeng@intel.com>; Tian, Feng
> <feng.tian@intel.com>
> Subject: Re: [edk2] correct way to reserve memory from PrePi?
> 
> I do not want to allocate the full memory range, just small parts of
> it. I have one or two ranges(depending on how the system config
> reports it) for all ram. e.g a 2gb device usually uses either
> 0x0000000-0x80000000 or 0x00000000-0x40000000 and
> 0x40000000-0x40000000.
> 
> So I digged even further and it looks like upon boot, the highest
> available memory resource descriptor is selected and allocated for the
> DxeCore.
> So if I have one memory resource only, the whole DRAM will be
> allocated by/for DxeCore. Is that really the intended behavior?
> Because this way I'm unable to reserve any RAM from the highest
> resource descriptor. The reason why it works when I have split the
> DRAM in two descriptors is that DxeCore will only allocate the upper
> half and I'm usually trying to reserve a few low memory ranges - which
> isn't always the case.
> 
> Thanks
> Michael
> 
> On Thu, Dec 15, 2016 at 5:55 AM, Gao, Liming <liming.gao@intel.com> wrote:
> > Michael:
> >   I understand your usage that BuildResourceDescriptorHob adds system
> memory range, BuildMemoryAllocationHob allocate the full memory range as
> reserved memory. Then, you expect they can be shown in EFI memory map.
> Right?
> >
> >   BuildResourceDescriptorHob() with (start,size) 0x80000000,0x80000000,
> then BuildMemoryAllocationHob() with (start,size) 0x80000000,0x80000000.
> It doesn't work.
> >   Two BuildResourceDescriptorHob() with (start,size)
> 0x80000000,0x40000000 and 0xc0000000,0x40000000, then two
> BuildMemoryAllocationHob(). It does work. Right?
> >
> > Thanks
> > Liming
> >> -----Original Message-----
> >> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> >> Michael Zimmermann
> >> Sent: Thursday, December 15, 2016 1:57 AM
> >> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >> Cc: edk2-devel@lists.01.org <edk2-devel@ml01.01.org>
> >> Subject: Re: [edk2] correct way to reserve memory from PrePi?
> >>
> >> I've enabled GCD debugging and apparently it doesn't accept the
> allocation:
> >>
> GCD:AllocateMemorySpace(Base=0000000090000000,Length=0000000010000
> >> 000)
> >>   GcdAllocateType = AtAddress
> >>   GcdMemoryType   = SystemMem
> >>   Alignment       = 0000000000000001
> >>   ImageHandle     = FDE28F90
> >>   DeviceHandle    = 0
> >> CoreAllocateSpaceCheckEntry:982 handle=FDE28F90
> >> CoreAllocateSpace:1130
> >>   Status = Not Found
> >> GCDMemType Range                             Capabilities
> >> Attributes
> >> ========== =================================
> >> ================
> >> ================
> >> NonExist   0000000000000000-000000007FFFFFFF 0000000000000000
> >> 0000000000000000
> >> SystemMem  0000000080000000-00000000FDFFFFFF 800000000000000E
> >> 0000000000000000*
> >> NonExist   00000000FE000000-00000000FE3FFFFF 0000000000000000
> >> 0000000000000000
> >> SystemMem  00000000FE400000-00000000FFFE5FFF 800000000000000E
> >> 0000000000000000
> >> SystemMem  00000000FFFE6000-00000000FFFEEFFF 800000000000000E
> >> 0000000000000000*
> >> SystemMem  00000000FFFEF000-00000000FFFFFFFF 800000000000000E
> >> 0000000000000000
> >>
> >>
> >> It fails in this line:
> >>
> https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Core/Dxe
> >> /Gcd/Gcd.c#L982
> >> In this example I've used(start,size) 0x80000000,0x80000000 for the
> >> resource descriptors.
> >> If I use 0x80000000,0x40000000 and 0xc0000000,0x40000000 everything
> >> works just fine.
> >>
> >> Thanks
> >> Michael
> >>
> >> On Wed, Dec 14, 2016 at 4:13 PM, Michael Zimmermann
> >> <sigmaepsilon92@gmail.com> wrote:
> >> > As far as I know the proper way is to create resource descriptors
> >> > using BuildResourceDescriptorHob and then allocate reserved areas
> >> > using BuildMemoryAllocationHob. This way I don't have any overlapping
> >> > descriptors - I just allocated some memory very early.
> >> >
> >> > I ran many tests and it looks like all calls to
> >> > BuildMemoryAllocationHob get ignored if my dram hobs look like this:
> >> > 0x00000000 - 0x40000000
> >> >
> >> > If I split this range into two Hob's like this everything seems to
> >> > work just fine:
> >> > 0x00000000 - 0x20000000
> >> > 0x20000000 - 0x20000000
> >> >
> >> > I took a look at other platforms like Juno and they add big dram Hob's
> >> > (2GB and 6GB) too so why is this a problem?
> >> >
> >> > Thanks
> >> > Michael
> >> >
> >> > On Wed, Dec 14, 2016 at 11:21 AM, Ard Biesheuvel
> >> > <ard.biesheuvel@linaro.org> wrote:
> >> >> On 14 December 2016 at 10:02, Michael Zimmermann
> >> >> <sigmaepsilon92@gmail.com> wrote:
> >> >>> I tried both BuildResourceDescriptorHob and
> BuildMemoryAllocationHob
> >> >>> but apparently they don't have any effect.
> >> >>> When I look at the output of the shell's memmap command there
> aren't
> >> >>> any reserved/unavailable pages.
> >> >>>
> >> >>> Furthermore, when using AllocatePages with one of the physical
> >> >>> addresses which I've reserved it succeeds which means that it's not
> >> >>> just a problem of how the memmap command works.
> >> >>>
> >> >>> Am I doing something wrong or is this a bug?
> >> >>>
> >> >>
> >> >> I think you need to ensure that they don't overlap existing resource
> >> >> descriptors: if you declare a region as reserved, you should not
> >> >> declare it as memory first
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