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[ Upstream commit 7ab57b76ebf632bf2231ccabe26bea33868118c6 ] We increase the default limit for buffer memory allocation by a factor of 10 to 640K to prevent data loss when using fast serial interfaces. For example when using RS485 without flow-control at speeds of 1Mbit/s an upwards we've run into problems such as applications being too slow to read out this buffer (on embedded devices based on imx53 or imx6). If you want to write transmitted data to a slow SD card and thus have realtime requirements, this limit can become a problem. That shouldn't be the case and 640K buffers fix such problems for us. This value is a maximum limit for allocation only. It has no effect on systems that currently run fine. When transmission is slow enough applications and hardware can keep up and increasing this limit doesn't change anything. It only _allows_ to allocate more than 2*64K in cases we currently fail to allocate memory despite having some. Signed-off-by: Manfred Schlaegl <manfred.schlaegl@ginzinger.com> Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.