741: using arm-gic to programm the ARM Generic Interrupt Controller r=stlankes a=stlankes

- add timer support
- using the counter-timer physical count register to determine a timestamp
- using rusty_demo to test the aarch64 port
- solves #738 

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

- add timer support
- using the counter-timer physical count register to determine a timestamp

736: revise TLS handling r=stlankes a=stlankes

- ARM used variant 1 of the TLS handling (see https://uclibc.org/docs/tls.pdf

)
- the previous version doesn't work correctly
- using an unsized struct to implement TLS like a C kernel

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

735: build(deps): bump anyhow from 1.0.70 to 1.0.71 r=stlankes a=dependabot[bot]

Bumps [anyhow](https://github.com/dtolnay/anyhow) from 1.0.70 to 1.0.71.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/dtolnay/anyhow/releases">anyhow's releases</a>.</em></p>
<blockquote>
<h2>1.0.71</h2>
<ul>
<li>Documentation improvements</li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/dtolnay/anyhow/commit/8b4fc43429fd9a034649e0f919c646ec6626c4c7"><code>8b4fc43</code></a> Release 1.0.71</li>
<li><a href="https://github.com/dtolnay/anyhow/commit/3c33b4b072045430857434a280f9238aef6a34bb"><code>3c33b4b</code></a> Merge pull request <a href="https://redirect.github.com/dtolnay/anyhow/issues/306">#306</a> from dtolnay/noinline</li>
<li><a href="https://github.com/dtolnay/anyhow/commit/d491b8884060508c6abaa911bf0abebd32469990"><code>d491b88</code></a> Mark format_err macro as doc(no_inline)</li>
<li>See full diff in <a href="https://github.com/dtolnay/anyhow/compare/1.0.70...1.0.71">compare view</a></li>
</ul>
</details>
<br />


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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

- ARM used variant 1 of the TLS handling (see
  https://uclibc.org/docs/tls.pdf)
- the previous version doesn't work correctly
- using an unsized struct to implement TLS like a C kernel

Bumps [anyhow](https://github.com/dtolnay/anyhow) from 1.0.70 to 1.0.71.
- [Release notes](https://github.com/dtolnay/anyhow/releases)
- [Commits](https://github.com/dtolnay/anyhow/compare/1.0.70...1.0.71

)

---
updated-dependencies:
- dependency-name: anyhow
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

734: revise assertion r=stlankes a=stlankes

On aarch64, the memory region below the kernel can be used for dynamic allocation.
Consequently, the assertion should allow this region.

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

On aarch64, the memory region below the kernel can be used for
dynamic allocation. Consequently, the assertion should allow
this region.

733: add RTC support and determine boot time r=stlankes a=stlankes



Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

732: revise aarch64 support r=stlankes a=stlankes

- add TLS support
- revise processor detection
- add function to switch the context
- revise stack handling
- initialize interrupt controller

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

- add TLS support
- revise processor detection
- add function to switch the context
- revise stack handling

- in addition, add some comments

731: don't leak memory if the environment is empty r=stlankes a=stlankes



Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

730: remove trailing null characters r=stlankes a=stlankes

- revert also #729 

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

- this character isn't required

This reverts commit f677532b.

729: remove typo r=stlankes a=stlankes



Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

728: move hardware independent function is_uhyve to env r=stlankes a=stlankes



Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

726: remove obsolete function `detect_from_uhyve` r=jounathaen a=stlankes

- minor improvements to #725
- removing obsolete code

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

725: don't initialize IO-APIC for uhyve r=jounathaen a=stlankes

uhyve doesn't support a common IO-APIC. Consequently, libhermit should not initialize the IO-APIC

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

uhyve doesn't support a common IO-APIC. Consequently, libhermit
should not initialize the IO-APIC

724: add check if the idle task has to give up the processor r=stlankes a=stlankes

- simplifies the run function of the scheduler
- avoids unneeded calls of the function `schedule`

Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

- only the idle task should call `run`
- consequently, the idle task check can be removed

723: remove deprecated functions and use hermit-dtb from crates.io r=stlankes a=stlankes



Co-authored-by: Stefan Lankes <slankes@eonerc.rwth-aachen.de>

719: Add basic docs for timer and semaphore syscalls r=stlankes a=nathanwhyte

Helping with issue #353

Added _(very)_ basic documentation to syscalls in [`timer.rs`](https://github.com/hermitcore/libhermit-rs/blob/master/src/syscalls/timer.rs) and [`semaphore.rs`](https://github.com/hermitcore/libhermit-rs/blob/master/src/syscalls/semaphore.rs

)

I used Linux man pages as a reference when writing these.

Co-authored-by: Nathan Whyte <nathanwhyte35@gmail.com>