[edk2-devel] [PATCH v3 3/5] OvmfPkg/Microvm/fdt: add empty fdt
Gerd Hoffmann
kraxel at redhat.com
Mon Dec 13 08:16:56 UTC 2021
FdtClient is unhappy without a device tree, so add an empty fdt
which we can use in case etc/fdt is not present in fw_cfg.
On ARM machines a device tree is mandatory for hardware detection,
thats why FdtClient fails hard.
On microvm the device tree is only used to detect virtio-mmio devices
(this patch series) and the pcie host (future series). So edk2 can
continue with limited functionality in case no device tree is present:
no storage, no network, but serial console and direct kernel boot
works.
qemu release 6.2 & newer will provide a device tree for microvm.
https://bugzilla.tianocore.org/show_bug.cgi?id=3689
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd at redhat.com>
---
OvmfPkg/PlatformPei/Platform.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
index c9ec1d7e99fb..d0323c645162 100644
--- a/OvmfPkg/PlatformPei/Platform.c
+++ b/OvmfPkg/PlatformPei/Platform.c
@@ -16,6 +16,7 @@
//
// The Library classes this module consumes
//
+#include <Library/BaseMemoryLib.h>
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/HobLib.h>
@@ -321,6 +322,18 @@ PciExBarInitialization (
);
}
+static const UINT8 EmptyFdt[] = {
+ 0xd0, 0x0d, 0xfe, 0xed, 0x00, 0x00, 0x00, 0x48,
+ 0x00, 0x00, 0x00, 0x38, 0x00, 0x00, 0x00, 0x48,
+ 0x00, 0x00, 0x00, 0x28, 0x00, 0x00, 0x00, 0x11,
+ 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x09,
+};
+
VOID
MicrovmInitialization (
VOID
@@ -335,8 +348,9 @@ MicrovmInitialization (
Status = QemuFwCfgFindFile ("etc/fdt", &FdtItem, &FdtSize);
if (EFI_ERROR (Status)) {
- DEBUG ((DEBUG_INFO, "%a: no etc/fdt found in fw_cfg\n", __FUNCTION__));
- return;
+ DEBUG ((DEBUG_INFO, "%a: no etc/fdt found in fw_cfg, using dummy\n", __FUNCTION__));
+ FdtItem = 0;
+ FdtSize = sizeof (EmptyFdt);
}
FdtPages = EFI_SIZE_TO_PAGES (FdtSize);
@@ -346,8 +360,12 @@ MicrovmInitialization (
return;
}
- QemuFwCfgSelectItem (FdtItem);
- QemuFwCfgReadBytes (FdtSize, NewBase);
+ if (FdtItem) {
+ QemuFwCfgSelectItem (FdtItem);
+ QemuFwCfgReadBytes (FdtSize, NewBase);
+ } else {
+ CopyMem (NewBase, EmptyFdt, FdtSize);
+ }
FdtHobData = BuildGuidHob (&gFdtHobGuid, sizeof (*FdtHobData));
if (FdtHobData == NULL) {
--
2.33.1
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