diff options
| author | Laszlo Ersek <lersek@redhat.com> | 2014-01-03 19:57:26 +0000 |
|---|---|---|
| committer | jljusten <jljusten@6f19259b-4bc3-4df7-8a09-765794883524> | 2014-01-03 19:57:26 +0000 |
| commit | 2ce7e221e70214b094e2e54d0e6dc9491a742dd3 (patch) | |
| tree | fbf13ce33ddf48b565ff6d20a60fb71cbf04d094 /OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c | |
| parent | 0dc231c9bd1a5aecfbcd373a50dc348a5dfbd38a (diff) | |
| download | edk2-platforms-2ce7e221e70214b094e2e54d0e6dc9491a742dd3.tar.xz | |
OvmfPkg: QemuFwCfgLib: extract stateful implementation
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
Diffstat (limited to 'OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c')
| -rw-r--r-- | OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c new file mode 100644 index 0000000000..f693cff29e --- /dev/null +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c @@ -0,0 +1,92 @@ +/** @file
+
+ Stateful and implicitly initialized fw_cfg library implementation.
+
+ Copyright (C) 2013, Red Hat, Inc.
+ Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
+
+ This program and the accompanying materials are licensed and made available
+ under the terms and conditions of the BSD License which accompanies this
+ distribution. The full text of the license may be found at
+ http://opensource.org/licenses/bsd-license.php
+
+ THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
+ WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+**/
+
+#include <Library/DebugLib.h>
+#include <Library/QemuFwCfgLib.h>
+
+STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
+
+
+/**
+ 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 ();
+}
+
+
+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;
+}
+
+
+/**
+ 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;
+}
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