Make standalone kernel actually standalone #58

tomaka · 2019-11-24T18:53:38Z

It is not possible to finish this PR.
It is mostly here for notes taking (i.e. looking at the changes later).

tomaka · 2019-11-25T18:02:23Z

Unfortunately it seems that the spin library doesn't compile for thumbv6m-none-eabi despite being no_std.

tomaka · 2019-11-25T19:48:41Z

For a reason I don't understand, trying to compile the freestanding kernel yields:

error: cannot produce bin for nametbd-standalone-kernel v0.1.0 (/home/pierre/Projets/os/kernel/standalone) as the target x86_64-unknown-none does not support these crate types

Even when I run rustc +nightly -Z unstable-options --print target-spec-json and copy-paste the result in the .json file, I get the same error.

EDIT: there was apparently some caching issue; cleaning my target directory fixed it

tomaka · 2019-11-25T20:32:44Z

Now running into:

LLVM ERROR: Do not know how to split the result of this operator!

rust-lang/rust#61721

This seems to be caused by +soft-float. Disabling this feature leads to linking errors instead.

tomaka · 2019-11-25T21:06:02Z

Notes for anyone who might find this page on Google:

I got rid of the __libc_csu_init, __libc_csu_fini and __libc_start_main symbols by passing -nostdlib to the linker.
aa1a0f7

tomaka · 2019-11-25T21:37:28Z

If the #[start] function isn't named _start with #[no_mangle] then everything gets stripped 🤔

Also, the following is generated for the main function, which is clearly wrong:

0000000000401010 <_ZN25nametbd_standalone_kernel4main17ha1b358a6a4062b4eE>:
  401010:       48 c7 04 25 c0 0f 00    movq   $0x0,0xfc0
  401017:       00 00 00 00 00 
  40101c:       48 c7 04 25 80 0f 00    movq   $0xfc0,0xf80
  401023:       00 c0 0f 00 00 
  401028:       48 c7 04 25 40 0f 00    movq   $0xf80,0xf40
  40102f:       00 80 0f 00 00 
  401034:       48 c7 04 25 00 0f 00    movq   $0xf40,0xf00
  40103b:       00 40 0f 00 00 
  401040:       48 c7 04 25 c0 0e 00    movq   $0xf00,0xec0
  401047:       00 00 0f 00 00 
  40104c:       48 c7 04 25 80 0e 00    movq   $0xec0,0xe80
  401053:       00 c0 0e 00 00 
  401058:       48 c7 04 25 40 0e 00    movq   $0xe80,0xe40
  40105f:       00 80 0e 00 00 
  401064:       48 c7 04 25 00 0e 00    movq   $0xe40,0xe00
  40106b:       00 40 0e 00 00 
  401070:       48 c7 04 25 c0 0d 00    movq   $0xe00,0xdc0
  401077:       00 00 0e 00 00 
  40107c:       48 c7 04 25 80 0d 00    movq   $0xdc0,0xd80
  401083:       00 c0 0d 00 00 
  401088:       48 c7 04 25 40 0d 00    movq   $0xd80,0xd40
  40108f:       00 80 0d 00 00 
  401094:       48 c7 04 25 00 0d 00    movq   $0xd40,0xd00
  40109b:       00 40 0d 00 00 
  4010a0:       48 c7 04 25 c0 0c 00    movq   $0xd00,0xcc0
  4010a7:       00 00 0d 00 00 
  4010ac:       48 c7 04 25 80 0c 00    movq   $0xcc0,0xc80
  4010b3:       00 c0 0c 00 00 
  4010b8:       48 c7 04 25 40 0c 00    movq   $0xc80,0xc40
  4010bf:       00 80 0c 00 00 
  4010c4:       48 c7 04 25 00 0c 00    movq   $0xc40,0xc00
  4010cb:       00 40 0c 00 00 
  4010d0:       48 c7 04 25 c0 0b 00    movq   $0xc00,0xbc0
  4010d7:       00 00 0c 00 00 
  4010dc:       48 c7 04 25 80 0b 00    movq   $0xbc0,0xb80
  4010e3:       00 c0 0b 00 00 
  4010e8:       48 c7 04 25 40 0b 00    movq   $0xb80,0xb40
  4010ef:       00 80 0b 00 00 
  4010f4:       48 c7 04 25 00 0b 00    movq   $0xb40,0xb00
  4010fb:       00 40 0b 00 00 
  401100:       48 c7 04 25 c0 0a 00    movq   $0xb00,0xac0
  401107:       00 00 0b 00 00 
  40110c:       48 c7 04 25 80 0a 00    movq   $0xac0,0xa80
  401113:       00 c0 0a 00 00 
  401118:       48 c7 04 25 40 0a 00    movq   $0xa80,0xa40
  40111f:       00 80 0a 00 00 
  401124:       48 c7 04 25 00 0a 00    movq   $0xa40,0xa00
  40112b:       00 40 0a 00 00 
  401130:       48 c7 04 25 c0 09 00    movq   $0xa00,0x9c0
  401137:       00 00 0a 00 00 
  40113c:       48 c7 04 25 80 09 00    movq   $0x9c0,0x980
  401143:       00 c0 09 00 00 
  401148:       48 c7 04 25 40 09 00    movq   $0x980,0x940
  40114f:       00 80 09 00 00 
  401154:       48 c7 04 25 00 09 00    movq   $0x940,0x900
  40115b:       00 40 09 00 00 
  401160:       48 c7 04 25 c0 08 00    movq   $0x900,0x8c0
  401167:       00 00 09 00 00 
  40116c:       48 c7 04 25 80 08 00    movq   $0x8c0,0x880
  401173:       00 c0 08 00 00 
  401178:       48 c7 04 25 40 08 00    movq   $0x880,0x840
  40117f:       00 80 08 00 00 
  401184:       48 c7 04 25 00 08 00    movq   $0x840,0x800
  40118b:       00 40 08 00 00 
  401190:       48 c7 04 25 c0 07 00    movq   $0x800,0x7c0
  401197:       00 00 08 00 00 
  40119c:       48 c7 04 25 80 07 00    movq   $0x7c0,0x780
  4011a3:       00 c0 07 00 00 
  4011a8:       48 c7 04 25 40 07 00    movq   $0x780,0x740
  4011af:       00 80 07 00 00 
  4011b4:       48 c7 04 25 00 07 00    movq   $0x740,0x700
  4011bb:       00 40 07 00 00 
  4011c0:       48 c7 04 25 c0 06 00    movq   $0x700,0x6c0
  4011c7:       00 00 07 00 00 
  4011cc:       48 c7 04 25 80 06 00    movq   $0x6c0,0x680
  4011d3:       00 c0 06 00 00 
  4011d8:       48 c7 04 25 40 06 00    movq   $0x680,0x640
  4011df:       00 80 06 00 00 
  4011e4:       48 c7 04 25 00 06 00    movq   $0x640,0x600
  4011eb:       00 40 06 00 00 
  4011f0:       48 c7 04 25 c0 05 00    movq   $0x600,0x5c0
  4011f7:       00 00 06 00 00 
  4011fc:       48 c7 04 25 80 05 00    movq   $0x5c0,0x580
  401203:       00 c0 05 00 00 
  401208:       48 c7 04 25 40 05 00    movq   $0x580,0x540
  40120f:       00 80 05 00 00 
  401214:       48 c7 04 25 00 05 00    movq   $0x540,0x500
  40121b:       00 40 05 00 00 
  401220:       48 c7 04 25 c0 04 00    movq   $0x500,0x4c0
  401227:       00 00 05 00 00 
  40122c:       48 c7 04 25 80 04 00    movq   $0x4c0,0x480
  401233:       00 c0 04 00 00 
  401238:       48 c7 04 25 40 04 00    movq   $0x480,0x440
  40123f:       00 80 04 00 00 
  401244:       48 c7 04 25 00 04 00    movq   $0x440,0x400
  40124b:       00 40 04 00 00 
  401250:       48 c7 04 25 c0 03 00    movq   $0x400,0x3c0
  401257:       00 00 04 00 00 
  40125c:       48 c7 04 25 80 03 00    movq   $0x3c0,0x380
  401263:       00 c0 03 00 00 
  401268:       48 c7 04 25 40 03 00    movq   $0x380,0x340
  40126f:       00 80 03 00 00 
  401274:       48 c7 04 25 00 03 00    movq   $0x340,0x300
  40127b:       00 40 03 00 00 
  401280:       48 c7 04 25 c0 02 00    movq   $0x300,0x2c0
  401287:       00 00 03 00 00 
  40128c:       48 c7 04 25 80 02 00    movq   $0x2c0,0x280
  401293:       00 c0 02 00 00 
  401298:       48 c7 04 25 40 02 00    movq   $0x280,0x240
  40129f:       00 80 02 00 00 
  4012a4:       48 c7 04 25 00 02 00    movq   $0x240,0x200
  4012ab:       00 40 02 00 00 
  4012b0:       48 c7 04 25 c0 01 00    movq   $0x200,0x1c0
  4012b7:       00 00 02 00 00 
  4012bc:       48 c7 04 25 80 01 00    movq   $0x1c0,0x180
  4012c3:       00 c0 01 00 00 
  4012c8:       48 c7 04 25 40 01 00    movq   $0x180,0x140
  4012cf:       00 80 01 00 00 
  4012d4:       48 c7 04 25 00 01 00    movq   $0x140,0x100
  4012db:       00 40 01 00 00 
  4012e0:       48 c7 04 25 c0 00 00    movq   $0x100,0xc0
  4012e7:       00 00 01 00 00 
  4012ec:       48 c7 04 25 80 00 00    movq   $0xc0,0x80
  4012f3:       00 c0 00 00 00 
  4012f8:       48 c7 04 25 40 00 00    movq   $0x80,0x40
  4012ff:       00 80 00 00 00 
  401304:       0f 0b                   ud2    
  401306:       0f 0b                   ud2

tomaka · 2019-11-25T21:40:57Z

Interestingly but not surprisingly, calling ALLOCATOR.init(0, ...) triggers a pretty big undefined behaviour, which is the reason why this was wrong.

However I'm now getting linking errors again after fixing this.

tomaka · 2019-11-25T21:55:37Z

Not sure how to get rid of memcpy, memmove, memcmp, memset, fmod and fmodf.

tomaka · 2019-11-27T16:42:54Z

The state of that is that it boots just fine. However once we start interpreting WASM code, in debug mode we get a panic (which I haven't identified yet), while in release mode we get undefined behaviours.

tomaka · 2019-11-27T17:50:04Z

Update: increased the stack size (it was only 8kiB), and now getting allocation errors from slab_allocator, in both debug and release.

Increasing the stack size seems to have fixed all the undefined behaviours.

tomaka · 2019-11-27T17:59:09Z

Using linked_list_allocator fixed the panics in the allocator.

This reverts commit ebe51e9.

This reverts commit 86fa6c0.

tomaka · 2019-11-27T18:04:08Z

I reverted the two dependabot commits, as things don't compile anymore on no_std after the version bumps.

tomaka · 2019-11-27T18:07:33Z

This is now ready for merging after clean up.

This reverts commit f980d44.

tomaka · 2019-11-27T19:36:50Z

Some issues to open after merging:

We just assume that 1G pages are supported by the CPU, but this isn't necessarily the case. Most notably QEMU doesn't set the appropriate flag in the CPUID (but still supports them), while BOCHS has them disabled by default.
We only identity-map the first 4GiB rather than 512GiB as expected, because the paging code is wrong.
There's no stack protection. In case of a stack overflow, bad things happen.
The heap is initialized to a local array. This works, but it should be dynamic. Also, increasing the heap size seems to make rustc crash, which isn't great.
The cleanness of the standalone kernel code is debatable and needs improvements.
qemu -cdrom ... works but qemu -kernel ... produces garbage. I'm not even sure that the entry point is being called at all.

tomaka added 3 commits November 24, 2019 19:52

Work-in-progress for no_std core

197e570

Merge branch 'master' into no-std-core

3c753e1

Use no-std version of wasmi

141576e

tomaka added 3 commits November 25, 2019 19:27

Merge remote-tracking branch 'origin/master' into no-std-core

0d8441e

More work

c1047d6

Rustfmt

2f5d56f

tomaka marked this pull request as ready for review November 25, 2019 19:38

Install rust-src

1f4f955

tomaka changed the title ~~Work-in-progress for no_std core~~ Make core compile for no_std Nov 25, 2019

More work

f33a9d2

tomaka added 5 commits November 25, 2019 21:47

It's compiling!

383853e

Make it work

0e82ed4

Rustfmt

44ccbfc

Remove fmod and fmodf

85f5a68

Remove these weird libc symbols

aa1a0f7

tomaka added 4 commits November 25, 2019 22:07

Don't build the standalone kernel for Linux

cd545da

Use a different cache for the standalone kernel

f8c0c0b

Rename job

926a8f8

Restore fmt::Display implementations

d37537b

tomaka changed the title ~~Make core compile for no_std~~ Make standalone kernel actually standalone Nov 25, 2019

Fix inconsistency in wasmi

d6789c9

tomaka added 2 commits November 25, 2019 22:44

Add Cargo.lock

f139e17

Tweak main.rs

d01edde

tomaka added 9 commits November 27, 2019 13:53

Prettier link script

5c22626

Tweak boot.S

a97fe49

Rename target to multiboot2

c0bc4c0

More tweaks

d12c02f

Pass multiboot header to kernel

d380ec5

Rename link script

66dd419

Correct target feature flags

d2bfa1f

Activate MMX/SSE/SSE2

764ece6

Rustfmt

e6a1e38

More work

551d43c

tomaka added 5 commits November 27, 2019 18:59

Change allocator

704b275

Rustfmt

58d6556

Revert "Bump parity-scale-codec from 1.0.6 to 1.1.0 (#69)"

e1b6026

This reverts commit ebe51e9.

Revert "Bump async-std from 1.0.0 to 1.1.0 (#67)"

d36bc66

This reverts commit 86fa6c0.

Merge branch 'master' into no-std-core

29f537c

tomaka added 7 commits November 27, 2019 19:29

Remove dependency on rand

c2c4a45

Remove compiler_builtins

f980d44

Fix grub.cfg

2028c21

Install lld

ae97028

Revert "Remove compiler_builtins"

563c57d

This reverts commit f980d44.

Some code clean up

262bec1

More work

816386d

tomaka merged commit 944f88f into master Nov 27, 2019

tomaka deleted the no-std-core branch November 27, 2019 19:55

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Make standalone kernel actually standalone #58

Make standalone kernel actually standalone #58

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Make standalone kernel actually standalone #58

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