Changyuan Lyu be495ec64a arch: x86_64: fix cpuid leaf 0x1 EBX bits 23-16 ...

Commit 5ec47d4883 was intended to patch ebx bits 23-16 in cpuid leaf
0x1, but it was not working as expected, as in rust, operator << has a
stronger precedence than & [1]. Later commit b6667f948e fixed the
operator precedence clippy warning, but did not fix the actual issue. As
a result, the current code is not changing ebx,

```
cpu_ebx |= ((dies_per_package as u32) * (cores_per_die as u32) * (threads_per_core as u32))
    & (0xff << 16);
```

Since the total number of logical processors is generally less than
65536, the right hand side of the expression is 0 in most cases.

[1] https://doc.rust-lang.org/reference/expressions.html#expression-precedence

Fixes: 5ec47d4883 ("arch: x86_64: enable HTT flag")
Signed-off-by: Changyuan Lyu <changyuanl@google.com>

2025-11-18 08:27:59 +00:00

..

src

arch: x86_64: fix cpuid leaf 0x1 EBX bits 23-16

2025-11-18 08:27:59 +00:00

Cargo.toml

misc: improve developer experience of cargo clippy

2025-11-17 16:59:49 +00:00