95252f9c04
Restore and document the forced initial POLLPRI event reporting when
poll() is used for the first time. This used to be the implemented
behavior before recent changes. Because of the way poll() is implemented,
this prevents losing an event happening between the last read() and the
first poll() invocation.
Since poll() for /dev/vcs* was not always supported, user space probes
for its availability as follows:
int fd = open("/dev/vcsa", O_RDONLY);
struct pollfd p = { .fd = fd, .events = POLLPRI };
available = (poll(&p, 1, 0) == 1);
Semantically, it makes sense to signal the first event as such even if
it might be spurious. The screen could be modified, and modified back
to its initial state before we get to read it, so users must be prepared
for that anyway.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.