Application launcher actions reference their applications by an index
into the global `g_apps` table. When skipping over settings apps,
we still have to increment the current app identifier.
The Settings app is basically a viewer for the Settings app category
anyway, so let's just direct users there instead of having the various
settings apps in the start menu.
When we get a COW fault and discover that whoever we were COW'ing
together with has either COW'ed that page on their end (or they have
unmapped/exited) we simplify life for ourselves by clearing the COW
bit and keeping the page we already have. (No need to COW if the page
is not shared!)
The act of doing this does not return a committed page to the pool.
In fact, that committed page we had reserved for this purpose was used
up (allocated) by our COW buddy when they COW'ed the page.
This fixes a kernel panic when running TestLibCMkTemp. :^)
This makes a kernel panic immediately fail the on-target CI job.
Otherwise the failed job looks like a test timeout unless one digs into
the details of the job.
We don't need an entirely separate VMObject subclass to influence the
location of the physical pages.
Instead, we simply allocate enough physically contiguous memory first,
and then pass it to the AnonymousVMObject constructor that takes a span
of physical pages.
Previously there was no way to create a MACAddress by passing a direct
address as a string. This will allow programs like the arp utility to
create a MACAddress instance by user-passed addresses.
VMObject already has an IntrusiveList of all the Regions that map it.
We were keeping a counter in addition to this, and only using it in
a single place to avoid iterating over the list in case it only had
1 entry.
Simplify VMObject by removing this counter and always iterating the
list even if there's only 1 entry. :^)
This was previously used for a single debug logging statement during
memory purging. There are no remaining users of this weak pointer,
so let's get rid of it.
If a purgeable VM object is in the "volatile" state when we're asked
to make a COW clone of it, make life simpler by simply "purging"
the cloned object right away.
This effectively means that a fork()'ed child process will discover
its purgeable+volatile regions to be empty if/when it tries making
them non-volatile.
This patch changes the semantics of purgeable memory.
- AnonymousVMObject now has a "purgeable" flag. It can only be set when
constructing the object. (Previously, all anonymous memory was
effectively purgeable.)
- AnonymousVMObject now has a "volatile" flag. It covers the entire
range of physical pages. (Previously, we tracked ranges of volatile
pages, effectively making it a page-level concept.)
- Non-volatile objects maintain a physical page reservation via the
committed pages mechanism, to ensure full coverage for page faults.
- When an object is made volatile, it relinquishes any unused committed
pages immediately. If later made non-volatile again, we then attempt
to make a new committed pages reservation. If this fails, we return
ENOMEM to userspace.
mmap() now creates purgeable objects if passed the MAP_PURGEABLE option
together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
Instead of crashing when we can't make the back buffer non-volatile,
we now transition the window into single-buffered mode instead
(assuming it was originally in double-buffered mode.)
This reduces GUI fidelity a bit (by potentially making windows flicker
during repaint) but since it's only triggered in low-memory conditions,
it seems like a reasonable thing to sacrifice in order for the system
to carry on.
This patch also stops us from allocating entirely new backing stores
after the old ones were purged. If they were purged but reallocated
just fine, there's no need to allocate new memory again. We already
have fresh zero-filled pages in the existing bitmap at this point.
Making a bitmap non-volatile after being volatile may fail to allocate
physical pages after the kernel stole the old pages in a purge.
This is different from the pages being purged, but reallocated. In that
case, they are simply replaced with zero-fill-on-demand pages as if
they were freshly allocated.
This was a really weird thing to begin with, purgeable bitmaps were
basically regular bitmaps without a physical memory reservation.
Since all the clients of this code ended up populating the bitmaps
with pixels immediately after allocating them anyway, there was no
need to avoid the reservation.
Instead, all Gfx::Bitmaps are now purgeable, in the sense that they
can be marked as volatile or non-volatile.
The only difference here is that allocation failure is surfaced when
we try to create the bitmap instead of during the handling of a
subsequent page fault.
This prevents GUI::TextBox and the `Paste & Go` action in the browser
from trying to paste a bitmap. Also, the paste action is enabled
and disabled on clipboard change to reflect if the clipboard data
can be pasted.
