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OvmfPkg: QemuFwCfgLib: extract stateful implementation

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The current implementation of QemuFwCfgLib is:
- stateful
- implicitly initialized in the library constructor.

OVMF's SEC runs from read-only memory/flash. When the library is linked
into a SEC binary (which currently never happens), the
"mQemuFwCfgSupported" global variable becomes read-only, making the
library non-functional.

Extract the stateful, implicitly initialized library implementation into a
separate file, making room for a stateless, explicitly queried
implementation that's usable in SEC. Restrict the stateful implementation
to the current, non-SEC clients.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15045 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek
2014-01-03 19:57:26 +00:00
committed by jljusten
parent 0dc231c9bd
commit 2ce7e221e7
3 changed files with 97 additions and 75 deletions
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74
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
View File

@@ -22,8 +22,6 @@
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
/**
Reads an 8-bit I/O port fifo into a block of memory.
@@ -78,26 +76,6 @@ IoWriteFifo8 (
);
/**
Returns a boolean indicating if the firmware configuration interface
is available or not.
This function may change fw_cfg state.
@retval TRUE The interface is available
@retval FALSE The interface is not available
**/
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
VOID
)
{
return InternalQemuFwCfgIsAvailable ();
}
/**
Selects a firmware configuration item for reading.
@@ -265,39 +243,6 @@ QemuFwCfgRead64 (
}
RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
VOID
)
{
UINT32 Signature;
UINT32 Revision;
//
// Enable the access routines while probing to see if it is supported.
//
mQemuFwCfgSupported = TRUE;
QemuFwCfgSelectItem (QemuFwCfgItemSignature);
Signature = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
Revision = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
(Revision < 1)
) {
DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
mQemuFwCfgSupported = FALSE;
return RETURN_SUCCESS;
}
DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
return RETURN_SUCCESS;
}
/**
Find the configuration item corresponding to the firmware configuration file.
@@ -349,22 +294,3 @@ QemuFwCfgFindFile (
return RETURN_NOT_FOUND;
}
/**
Returns a boolean indicating if the firmware configuration interface is
available for library-internal purposes.
This function never changes fw_cfg state.
@retval TRUE The interface is available internally.
@retval FALSE The interface is not available internally.
**/
BOOLEAN
EFIAPI
InternalQemuFwCfgIsAvailable (
VOID
)
{
return mQemuFwCfgSupported;
}