tyler.durden
/
audk
mirror of https://github.com/acidanthera/audk.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

OvmfPkg/QemuFlashFvbServicesRuntimeDxe: refine flash detection 

Flash can be write-protected in qemu (which is usually the case for
code).  In case the variable store flash block is configured read-only
ovmf wouldn't be able to store EFI variables there, so not setting up
fvb in that case (and fallhack to emulation) is the better option.
It'll avoid problems later due to flash writes failing.

The patch tries to write back the original value read earlier, so flash
content doesn't change in case the write succeeds.  But the status we
read back after the attempt to write will tell us whenever flash is
writable or not.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Gerd Hoffmann 2023-06-01 08:08:03 +02:00 committed by mergify[bot]
parent 4e5a804222
commit 578a715cfc
1 changed files with 11 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
View File

@ -114,9 +114,17 @@ QemuFlashDetected (
DEBUG ((DEBUG_INFO, "QemuFlashDetected => FD behaves as RAM\n"));
*Ptr = OriginalUint8;
} else if (ProbeUint8 == CLEARED_ARRAY_STATUS) {
DEBUG ((DEBUG_INFO, "QemuFlashDetected => FD behaves as FLASH\n"));
FlashDetected = TRUE;
*Ptr = READ_ARRAY_CMD;
*Ptr = WRITE_BYTE_CMD;
*Ptr = OriginalUint8;
*Ptr = READ_STATUS_CMD;
ProbeUint8 = *Ptr;
*Ptr = READ_ARRAY_CMD;
if (ProbeUint8 & 0x10 /* programming error */) {
DEBUG ((DEBUG_INFO, "QemuFlashDetected => FD behaves as FLASH, write-protected\n"));
} else {
DEBUG ((DEBUG_INFO, "QemuFlashDetected => FD behaves as FLASH, writable\n"));
FlashDetected = TRUE;
}
}
}