[edk2-devel] [PATCH 1/1] OvmfPkg/PlatformInitLib: limit phys-bits to 46.
Gerd Hoffmann
kraxel at redhat.com
Thu Jun 1 07:57:31 UTC 2023
Older linux kernels have problems with phys-bits larger than 46,
ubuntu 18.04 (kernel 4.15) has been reported to be affected.
Reduce phys-bits limit from 47 to 46.
Reported-by: Fiona Ebner <f.ebner at proxmox.com>
Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
---
OvmfPkg/Library/PlatformInitLib/MemDetect.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
index 1102b00ecbf0..662e7e85bbc5 100644
--- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
+++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
@@ -646,16 +646,19 @@ PlatformAddressWidthFromCpuid (
));
if (Valid) {
- if (PhysBits > 47) {
+ if (PhysBits > 46) {
/*
* Avoid 5-level paging altogether for now, which limits
* PhysBits to 48. Also avoid using address bit 48, due to sign
* extension we can't identity-map these addresses (and lots of
* places in edk2 assume we have everything identity-mapped).
* So the actual limit is 47.
+ *
+ * Also some older linux kernels apparently have problems handling
+ * phys-bits > 46 correctly, so use that as limit.
*/
- DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 47 (avoid 5-level paging)\n", __func__));
- PhysBits = 47;
+ DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 46 (avoid 5-level paging)\n", __func__));
+ PhysBits = 46;
}
if (!Page1GSupport && (PhysBits > 40)) {
--
2.40.1
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