Re: [Xen-devel] [PATCH v2 08/29] ArmVirtualizationPkg: add padding to FDT allocation

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

On 28 January 2015 at 15:13, Olivier Martin <olivier.martin@xxxxxxx> wrote:
> Same question as last time, would it not be better to have a PCD instead of
> hardcoded value?

Ah yes, I remember reading that but failed to take it into account.

> Some platforms might want to have a larger FDT padding.
>

Agreed. Will add it to v3


>
>> -----Original Message-----
>> From: Ard Biesheuvel [mailto:ard.biesheuvel@xxxxxxxxxx]
>> Sent: 26 January 2015 19:03
>> To: edk2-devel@xxxxxxxxxxxxxxxxxxxxx; lersek@xxxxxxxxxx; Olivier
>> Martin; roy.franz@xxxxxxxxxx; leif.lindholm@xxxxxxxxxx;
>> stefano.stabellini@xxxxxxxxxxxxx; Ian.Campbell@xxxxxxxxxx;
>> anthony.perard@xxxxxxxxxx; christoffer.dall@xxxxxxxxxx; xen-
>> devel@xxxxxxxxxxxxx; ilias.biris@xxxxxxxxxx
>> Cc: Ard Biesheuvel
>> Subject: [PATCH v2 08/29] ArmVirtualizationPkg: add padding to FDT
>> allocation
>>
>> Our primary user QEMU/mach-virt presents us with a FDT blob padded
>> to 64 KB with plenty of room to set additional properties. However,
>> in the general case, we should only add properties after making sure
>> there is enough room available.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> ---
>>
>> ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiL
>> ib.c | 17 ++++++++++++++---
>>  1 file changed, 14 insertions(+), 3 deletions(-)
>>
>> diff --git
>> a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPe
>> iLib.c
>> b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPe
>> iLib.c
>> index c500d5964b25..42a87309aebe 100644
>> ---
>> a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPe
>> iLib.c
>> +++
>> b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPe
>> iLib.c
>> @@ -24,6 +24,15 @@
>>  #include <Guid/EarlyPL011BaseAddress.h>
>>  #include <Guid/FdtHob.h>
>>
>> +//
>> +// We may want to apply some changes to the device tree before passing
>> it
>> +// to the OS: for instance, if we find a PL031 RTC node and attach our
>> +// runtime driver to it, we should disable it in the device tree by
>> setting
>> +// its status property to "disabled". Add some padding to make sure
>> this is
>> +// possible.
>> +//
>> +#define FDT_PADDING   256
>> +
>>  EFI_STATUS
>>  EFIAPI
>>  PlatformPeim (
>> @@ -33,6 +42,7 @@ PlatformPeim (
>>    VOID               *Base;
>>    VOID               *NewBase;
>>    UINTN              FdtSize;
>> +  UINTN              FdtPages;
>>    UINT64             *FdtHobData;
>>    UINT64             *UartHobData;
>>    INT32              Node, Prev;
>> @@ -47,10 +57,11 @@ PlatformPeim (
>>    ASSERT (Base != NULL);
>>    ASSERT (fdt_check_header (Base) == 0);
>>
>> -  FdtSize = fdt_totalsize (Base);
>> -  NewBase = AllocatePages (EFI_SIZE_TO_PAGES (FdtSize));
>> +  FdtSize = fdt_totalsize (Base) + FDT_PADDING;
>> +  FdtPages = EFI_SIZE_TO_PAGES (FdtSize);
>> +  NewBase = AllocatePages (FdtPages);
>>    ASSERT (NewBase != NULL);
>> -  CopyMem (NewBase, Base, FdtSize);
>> +  fdt_open_into (Base, NewBase, EFI_PAGES_TO_SIZE (FdtPages));
>>
>>    FdtHobData = BuildGuidHob (&gFdtHobGuid, sizeof *FdtHobData);
>>    ASSERT (FdtHobData != NULL);
>> --
>> 1.8.3.2
>>
>
>
>
>

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