lib: disable usbfs zero-copy support by default

Although we added a detection mechanism for the presence of the Kernel
bug earlier, reading from the incorrectly mapped memory might cause a
bus error on some ARM systems.

With the overall performance benefit being rather minimal for the
data rates of rtl-sdr, disable zero-copy by default.
master
Steve Markgraf 3 years ago
parent be1d1206bf
commit 81833a1cf6
  1. 8
      CMakeLists.txt
  2. 6
      configure.ac
  3. 2
      src/librtlsdr.c

@ -126,6 +126,14 @@ else (DETACH_KERNEL_DRIVER)
message (STATUS "Building with kernel driver detaching disabled, use -DDETACH_KERNEL_DRIVER=ON to enable")
endif (DETACH_KERNEL_DRIVER)
option(ENABLE_ZEROCOPY "Enable usbfs zero-copy support" OFF)
if (ENABLE_ZEROCOPY)
message (STATUS "Building with usbfs zero-copy support enabled")
add_definitions(-DENABLE_ZEROCOPY=1)
else (ENABLE_ZEROCOPY)
message (STATUS "Building with usbfs zero-copy support disabled, use -DENABLE_ZEROCOPY=ON to enable")
endif (ENABLE_ZEROCOPY)
########################################################################
# Add subdirectories
########################################################################

@ -101,6 +101,12 @@ AC_ARG_ENABLE(driver-detach,
CFLAGS="$CFLAGS -DDETACH_KERNEL_DRIVER"
fi])
AC_ARG_ENABLE(zerocopy,
[ --enable-zerocopy Enable usbfs zero-copy support (disabled by default)],
[if test x$enableval = xyes; then
CFLAGS="$CFLAGS -DENABLE_ZEROCOPY"
fi])
dnl Generate the output
AC_CONFIG_HEADER(config.h)

@ -1751,7 +1751,7 @@ static int _rtlsdr_alloc_async_buffers(rtlsdr_dev_t *dev)
dev->xfer_buf = malloc(dev->xfer_buf_num * sizeof(unsigned char *));
memset(dev->xfer_buf, 0, dev->xfer_buf_num * sizeof(unsigned char *));
#if defined (__linux__) && LIBUSB_API_VERSION >= 0x01000105
#if defined(ENABLE_ZEROCOPY) && defined (__linux__) && LIBUSB_API_VERSION >= 0x01000105
fprintf(stderr, "Allocating %d zero-copy buffers\n", dev->xfer_buf_num);
dev->use_zerocopy = 1;

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