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decf89f86e
When allocating crash kernel region without explicitly specifying its
base address/size, memblock_phys_alloc_range will attempt to allocate
memory top to bottom (memblock.bottom_up is false), so the crash
kernel region will end up in highmem on 64bit systems. This way
swiotlb can't work on the crash kernel, since there won't be any
32bit addressible memory available for the bounce buffers.
Try to allocate 32bit addressible memory if available, for the
crash kernel by restricting the top search address to be less
than SZ_4G. If that fails fallback to the previous behavior.
I tested this on HiFive Unmatched where the pci-e controller needs
swiotlb to work, with this patch it's possible to access the pci-e
controller on crash kernel and mount the rootfs from the nvme.
Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
Fixes: e53d28180d ("RISC-V: Add kdump support")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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.