023a547dc6
Spotted while reading through the VM code while thinking about how to
implement vfork().
When axeld disabled this in 2005 (!), Haiku's kernel was still young,
BeOS drivers were still "a thing," and there was no distinction in this
function from being called by the kernel / not by the kernel.
Now, it's 2018, we manage all drivers ourselves, have SMAP enabled by
default when available, and as axeld recently noted on the mailing lists,
"there's not much reason we still use GCC2 for the kernel anyway." So we
probably don't care about any BeOS drivers that may be broken by this
(are there any still around?)
Besides the usual fixes to get this 13-year-old chunk to work again, there
are two functional changes:
1) Allow the kernel to clone whatever it likes into the user's address space.
It seems that this is often done legitimately (e.g. team creation), and
so attempting to distinguish those cases seems more work than it may be
worth right now.
The disadvantage is that drivers without proper checks may be "tricked"
into cloning areas they shouldn't; but I'm guessing if that's the case,
then something else is probably broken and the driver should be fixed.
It seems the reverse case (cloning a userland area into the kernel)
is much more common (in fact, it looks like all 4 of the 4 places
where clone_area is used in kernel-space outside the kernel itself
are doing this.)
2) At KDEBUG_LEVEL 2 and higher, throw a panic when attempting to clone
an area that does not have the protection flag set. This should make
finding any bugs exposed by this change much easier than "hardware doesn't
work" / "black screen on boot" / etc., as well as any potential future
bugs introduced in the process of driver development.
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|---|---|---|
| 3rdparty | ||
| build | ||
| data | ||
| docs | ||
| headers | ||
| src | ||
| .editorconfig | ||
| .gitignore | ||
| .gitreview | ||
| configure | ||
| Jamfile | ||
| Jamrules | ||
| License.md | ||
| ReadMe.Compiling.md | ||
| ReadMe.md | ||
Haiku
Homepage | Mailing Lists | IRC Channels | Issue Tracker | API docs
Haiku is an open-source operating system that specifically targets personal computing. Inspired by the BeOS, Haiku is fast, simple to use, easy to learn and yet very powerful.
Goals
- Sensible defaults with minimal configuration required.
- Clean, clear, concise code.
- Unified desktop environment.
Trying Haiku
Haiku provides pre-built nightly images and release images. Haiku is compatible with a large variety of hardware, but in case you don't want to "take the plunge" and install Haiku on bare metal, you can install it on a virtual machine (VM) instead. If you've never used a VM before, you can follow one of the "Emulating Haiku" guides.
Compiling Haiku
See ReadMe.Compiling.
Contributing
Haiku is a meritocratic open source project with a large variety of tasks. Even if you can't write code, you can still help! Haiku needs designers, (technical) writers, translators, testers... Get involved and help out!
Contributing code
If you're submitting a patch to us, please make sure you're following the patch submitting guidelines.
If you're having trouble finding something in the source tree, you can use one of our OpenGrok servers:
- http://xref.plausible.coop/ (provided by Landon Fuller)
- http://code.metager.de/source/xref/haiku (provided by MetaGer)
Contributing documentation
The main piece of documentation that still needs work are the API docs (found
in the tree at docs/user). Just find an undocumented class, write
documentation for it, and submit a patch.
Contributing translations
See wiki:i18n.
Contributing software ports
See HaikuPorts.
Contributing to our infrastructure
See Infrastructure.