[edk2-devel] [PATCH v2 3/3] RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection
Yao, Jiewen
jiewen.yao at intel.com
Thu Aug 26 16:40:23 UTC 2021
Good idea, Ard.
> ASSERT_EFI_ERROR (Status);
> ASSERT (LowerMemorySize > 0);
I like this suggestion.
Thank you
Yao Jiewen
> -----Original Message-----
> From: Ard Biesheuvel <ardb at kernel.org>
> Sent: Thursday, August 26, 2021 7:15 PM
> To: Gerd Hoffmann <kraxel at redhat.com>
> Cc: edk2-devel-groups-io <devel at edk2.groups.io>; Ard Biesheuvel
> <ardb+tianocore at kernel.org>; Yao, Jiewen <jiewen.yao at intel.com>; Justen,
> Jordan L <jordan.l.justen at intel.com>; Philippe Mathieu-Daude
> <philmd at redhat.com>
> Subject: Re: [PATCH v2 3/3] RFC: OvmfPkg/PlatformPei: stop using cmos for
> memory detection
>
> On Thu, 26 Aug 2021 at 11:55, Gerd Hoffmann <kraxel at redhat.com> wrote:
> >
> > Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
> >
> > Not needed for qemu 1.7 (released in 2013) and newer.
> >
> > Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> > ---
> > OvmfPkg/PlatformPei/MemDetect.c | 58 ++-------------------------------
> > 1 file changed, 3 insertions(+), 55 deletions(-)
> >
> > diff --git a/OvmfPkg/PlatformPei/MemDetect.c
> b/OvmfPkg/PlatformPei/MemDetect.c
> > index 20154255324b..8d2c7f432472 100644
> > --- a/OvmfPkg/PlatformPei/MemDetect.c
> > +++ b/OvmfPkg/PlatformPei/MemDetect.c
> > @@ -37,7 +37,6 @@ Module Name:
> > #include <Library/QemuFwCfgSimpleParserLib.h>
> >
> > #include "Platform.h"
> > -#include "Cmos.h"
> >
> > UINT8 mPhysMemAddressWidth;
> >
> > @@ -295,52 +294,11 @@ GetSystemMemorySizeBelow4gb (
> > {
> > EFI_STATUS Status;
> > UINT64 LowerMemorySize = 0;
> > - UINT8 Cmos0x34;
> > - UINT8 Cmos0x35;
> >
> > Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
> > - if (Status == EFI_SUCCESS && LowerMemorySize > 0) {
> > - return LowerMemorySize;
> > - }
> > + ASSERT (Status == EFI_SUCCESS && LowerMemorySize > 0);
>
> Nit: better to do
>
> ASSERT_EFI_ERROR (Status);
> ASSERT (LowerMemorySize > 0);
>
> so that you can tell from the debug log which condition triggered, and
> if it is the first one, what the actual error code was.
>
>
> > + return LowerMemorySize;
> >
> > - //
> > - // CMOS 0x34/0x35 specifies the system memory above 16 MB.
> > - // * CMOS(0x35) is the high byte
> > - // * CMOS(0x34) is the low byte
> > - // * The size is specified in 64kb chunks
> > - // * Since this is memory above 16MB, the 16MB must be added
> > - // into the calculation to get the total memory size.
> > - //
> > -
> > - Cmos0x34 = (UINT8) CmosRead8 (0x34);
> > - Cmos0x35 = (UINT8) CmosRead8 (0x35);
> > -
> > - return (UINT32) (((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) +
> SIZE_16MB);
> > -}
> > -
> > -
> > -STATIC
> > -UINT64
> > -GetSystemMemorySizeAbove4gb (
> > - )
> > -{
> > - UINT32 Size;
> > - UINTN CmosIndex;
> > -
> > - //
> > - // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
> > - // * CMOS(0x5d) is the most significant size byte
> > - // * CMOS(0x5c) is the middle size byte
> > - // * CMOS(0x5b) is the least significant size byte
> > - // * The size is specified in 64kb chunks
> > - //
> > -
> > - Size = 0;
> > - for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {
> > - Size = (UINT32) (Size << 8) + (UINT32) CmosRead8 (CmosIndex);
> > - }
> > -
> > - return LShiftU64 (Size, 16);
> > }
> >
> >
> > @@ -371,12 +329,9 @@ GetFirstNonAddress (
> > // If QEMU presents an E820 map, then get the highest exclusive >=4GB RAM
> > // address from it. This can express an address >= 4GB+1TB.
> > //
> > - // Otherwise, get the flat size of the memory above 4GB from the CMOS
> (which
> > - // can only express a size smaller than 1TB), and add it to 4GB.
> > - //
> > Status = ScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
> > if (EFI_ERROR (Status)) {
> > - FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();
> > + FirstNonAddress = BASE_4GB;
> > }
> >
> > //
> > @@ -719,7 +674,6 @@ QemuInitializeRam (
> > )
> > {
> > UINT64 LowerMemorySize;
> > - UINT64 UpperMemorySize;
> > MTRR_SETTINGS MtrrSettings;
> > EFI_STATUS Status;
> >
> > @@ -775,12 +729,6 @@ QemuInitializeRam (
> > // memory size read from the CMOS.
> > //
> > Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
> > - if (EFI_ERROR (Status)) {
> > - UpperMemorySize = GetSystemMemorySizeAbove4gb ();
> > - if (UpperMemorySize != 0) {
> > - AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
> > - }
> > - }
> > }
> >
> > //
> > --
> > 2.31.1
> >
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