Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
![]() On some architectures (e.g. arm64) requests for IO coherent memory may use non-cachable attributes if the relevant device isn't cache coherent. If these pages are then remapped into userspace as cacheable, they may not be coherent with the non-cacheable mappings. In particular this happens with libusb, when it attempts to create zero-copy buffers for use by rtl-sdr (https://github.com/osmocom/rtl-sdr/). On low end arm devices with non-coherent USB ports, the application will be unexpectedly killed, while continuing to work fine on arm machines with coherent USB controllers. This bug has been discovered/reported a few times over the last few years. In the case of rtl-sdr a compile time option to enable/disable zero copy was implemented to work around it. Rather than relaying on application specific workarounds, dma_mmap_coherent() can be used instead of remap_pfn_range(). The page cache/etc attributes will then be correctly set in userspace to match the kernel mapping. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20200504201348.1183246-1-jeremy.linton@arm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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arch | ||
block | ||
certs | ||
crypto | ||
Documentation | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
LICENSES | ||
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 |
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.