menu "DCCP CCIDs Configuration"
config IP_DCCP_CCID2_DEBUG
bool "CCID-2 debugging messages"
---help---
Enable CCID-2 specific debugging messages.
The debugging output can additionally be toggled by setting the
ccid2_debug parameter to 0 or 1.
If in doubt, say N.
config IP_DCCP_CCID3
bool "CCID-3 (TCP-Friendly)"
def_bool y if (IP_DCCP = y || IP_DCCP = m)
---help---
CCID-3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
rate-controlled congestion control mechanism. TFRC is designed to
be reasonably fair when competing for bandwidth with TCP-like flows,
where a flow is "reasonably fair" if its sending rate is generally
within a factor of two of the sending rate of a TCP flow under the
same conditions. However, TFRC has a much lower variation of
throughput over time compared with TCP, which makes CCID-3 more
suitable than CCID-2 for applications such streaming media where a
relatively smooth sending rate is of importance.
CCID-3 is further described in RFC 4342,
http://www.ietf.org/rfc/rfc4342.txt
The TFRC congestion control algorithms were initially described in
RFC 5348.
This text was extracted from RFC 4340 (sec. 10.2),
http://www.ietf.org/rfc/rfc4340.txt
If in doubt, say N.
config IP_DCCP_CCID3_DEBUG
bool "CCID-3 debugging messages"
depends on IP_DCCP_CCID3
---help---
Enable CCID-3 specific debugging messages.
The debugging output can additionally be toggled by setting the
ccid3_debug parameter to 0 or 1.
If in doubt, say N.
config IP_DCCP_TFRC_LIB
def_bool y if IP_DCCP_CCID3
config IP_DCCP_TFRC_DEBUG
def_bool y if IP_DCCP_CCID3_DEBUG
endmenu
f='/cgit.cgi/linux/net-next.git/refs/?h=nds-private-remove&id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>refslogtreecommitdiff
efi/fdt: Avoid FDT manipulation after ExitBootServices()
Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.
Commit:
abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().
Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.
So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)
Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.
Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Riku Voipio <riku.voipio@linaro.org>
Cc: <stable@vger.kernel.org>
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>