summary refs log tree commit diff stats
path: root/gitlab/issues_text/target_i386/host_missing/accel_TCG/661
blob: 5b1f1b34a1276e38a4d20baff237df2dc807e9b7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Unable to enable 5 level paging
Description of problem:
When attempting to set cr4.LA57, qemu just freezes on that instruction. When I say freeze I mean literally freeze, no exceptions, nothing, it just halts forever on that instruction. When this happened, the first thing I did was

```
(qemu) info registers 
EAX=00001000 EBX=00000001 ECX=80224f08 EDX=00000000
ESI=8034a3a0 EDI=00026520 EBP=000079f8 ESP=000079c8
EIP=00019648 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0020 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
CS =0018 00000000 ffffffff 00c09a00 DPL=0 CS32 [-R-]
SS =0020 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0020 00000000 ffffffff 00c09300 DPL=0 DS   [-WA]
FS =0020 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
GS =0020 00000000 ffffffff 00cf9300 DPL=0 DS   [-WA]
LDT=0000 00000000 00000000 00008200 DPL=0 LDT
TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
GDT=     0000e120 00000037
IDT=     00000000 00000000
CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
DR6=00000000ffff0ff0 DR7=0000000000000400
EFER=0000000000000000
...
```

then using gdb to figure out what instruction it is hanging on, I set a breakpoint at 0x19648 at and ran 
```
(gdb) x/1 0x19648
=> 0x19648:	mov    %rax,%cr4
(gdb) 
```

This instruction corresponds to this LOC within limine https://github.com/limine-bootloader/limine/blob/trunk/stage23/protos/stivale.32.c#L33
Steps to reproduce:
1. Try to enable 5 level paging
2. qemu freezes when trying to set cr4.LA57
3. cry
Additional information:
This never happened prior to version 6.1, I test this on multiple different machines and a few of my friends 
experienced the same issue

I have not tested this on linux, however I assume it will do the same on anything else. 
Either way, qemu should not be just halting