Re: ARM PrePI Memory setup recommendations

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 8 August 2016 at 11:18, Michael Zimmermann <sigmaepsilon92@gmail.com> wrote:
> I'm using the defaults from the (now deleted) 2ndstage sample dsc:
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiACPIReclaimMemory|0
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiACPIMemoryNVS|0
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiReservedMemoryType|0
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesData|50
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiRuntimeServicesCode|20
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiBootServicesCode|400
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiBootServicesData|20000

20000 pages == 80 MB, so this value makes little sense if you have 32
MB of memory. Dropping this to a sane value fixed some problems we saw
with QEMU when running with the default 128 MB

>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiLoaderCode|20
>   gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiLoaderData|0
>
> I figured that the PrePi's stack setup may cause this, especially since I'm
> using all the memory up to 0xFFFFFFFF+1 which causes the logic to ignore the
> last page(I think).
> I'm now using PcdSystemMemorySize - PcdFdSize - EFI_PAGE_SIZE which seems to
> work pretty good even though the "missing" memory was just like 900bytes and
> not 4096.
>
> Thanks
> Michael
>
> On Mon, Aug 8, 2016 at 10:50 AM, Ard Biesheuvel <ard.biesheuvel@linaro.org>
> wrote:
>>
>> On 6 August 2016 at 13:05, Michael Zimmermann <sigmaepsilon92@gmail.com>
>> wrote:
>> > Hi,
>> >
>> > I have some problems with my current setup and would like to ask you for
>> > the
>> > best way to configure the following setup:
>> > - I'm using PrePi, I don't need relocations because the loading address
>> > is
>> > fixed(0xfe000000)
>> > - The SystemMemory address range is unknown at compile time
>> > - the system-memory consists of multiple ranges with holes so providing
>> > just
>> > a base and a size is not enough
>> > - There's no NOR, edk2 gets loaded into dram
>> >
>> > my current setup:
>> > PcdSystemMemoryBase = loading addr(0xfe000000)
>> > PcdSystemMemorySize = 32MB
>> > FD_BASE = PcdSystemMemoryBase
>> > FD_SIZE = 4MB
>> > in ArmPlatformGetVirtualMemoryMap I call BuildResourceDescriptorHob for
>> > all
>> > DRAM memory ranges.
>> > In PrePiMain after MemoryPeim I call BuildMemoryAllocationHob for some
>> > reserved memory ranges
>> >
>> > After running into out-of-memory errors during PrePi when using bigger
>> > FV's
>> > I revisited everything and came across a PCD I somehow never looked at
>> > when
>> > setting up my platform a year ago: PcdSystemMemoryUefiRegionSize.
>> > this was hardcoded to 0x00e00000 which obviously caused allocation
>> > errors
>> > while extracting big FV's even though PcdSystemMemorySize was big
>> > enough.
>> >
>> > Since there already was this nice comment 'PcdSystemMemorySize -
>> > PcdFdSize'
>> > I did exactly that: 32MB-4MB = 28MB.
>> > Unfortunately after doing that MdeModulePkg/Core/Dxe/Gcd/Gcd.c starts
>> > bugging that he can't find a resource hob that contains the PHIT Hob.
>> >
>>
>> Could you check the
>>
>> gEmbeddedTokenSpaceGuid.PcdMemoryTypeEfiXXX|nnnn
>>
>> definitions in your .DSC? Fairly recently, the core code was modified
>> to use the sum of these definitions as an estimate of the minimally
>> required allocation size, and it broke some other platforms in a
>> similar way.
>>
>> > So now that my setup and problems are clear, the questions:
>> > - Is it ok to define ResourceHob's that cover the PcdSystemMemory range?
>> > - what can I do to fix the PHIT Hob problem? should PcdFdSize +
>> > PcdSystemMemoryUefiRegionSize be smaller than PcdSystemMemorySize ?
>> > - I took a quick look at ArmVirt where they change the PcdSystemMemory
>> > range
>> > at runtime, but they use lots of custom code like their own
>> > MemoryPeiLib,
>> > and I think everything but Xen uses PEIM instead of PrePi. Also as I
>> > said I
>> > have more than one range so this would work anyway.
>> >
>>
>> ArmVirtQemu uses PEIM, since it runs from [emulated] NOR flash.
>> ArmVirtQemuKernel and ArmVirtXen use PrePi (the former is simply
>> ArmVirtQemu with the FD executing from DRAM, using the QEMU '-kernel'
>> option)
>
>