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OvmfPkg/Microvm/fdt: add empty fdt 

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,
that's 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.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3689
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>
This commit is contained in:
Gerd Hoffmann 2021-12-13 09:16:56 +01:00 committed by mergify[bot]
parent 79dcaf7054
commit c802f8935c
1 changed files with 22 additions and 4 deletions
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26
OvmfPkg/PlatformPei/Platform.c
View File

@ -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) {