[PATCH 21/21] ARM: Kirkwood: Remove DT support

On Fri, 2014-02-21 at 14:07 +0100, Arnd Bergmann wrote:

On Friday 21 February 2014 01:47:31 Ben Hutchings wrote:

quoted

On Thu, 2014-02-20 at 16:19 +0100, Arnd Bergmann wrote:

quoted

On Thursday 20 February 2014 14:21:10 Ian Campbell wrote:

quoted

For all I know, the only interesting ixp4xx platforms are the consumer
products listed on http://www.nslu2-linux.org/, the other ones you support
are development boards that tend to exist only in very small quantities.

The main limitation would be the amount of installed RAM, which is
either 32MB or 64MB depending on the machine for these. Running a
modern Debian with these constraints is probably possible but
doesn't sound like fun. 

Our most pressing constraint has actually been the size of the kernel
partition in flash, which is only ~1.4 MB on some of the iop32x and
ixp4xx machines (and ~1.5 MB on one of the orion5x machines).  We've
modularised as much as possible and turned off some of the features that
are otherwise standard across all Debian architectures.

Makes sense. I'm impressed you actually manage to get a modern kernel
in 1.5MB and have it boot up a (mostly) full distro. I think we have
in the past dropped a subarchitecture from the kernel when it turned
out its defconfig could no longer fit within the 2MB of flash it
has.

[...]

These are the changes we make for orion5x:

# CONFIG_KPROBES is not set
# CONFIG_CRYPTO_FIPS is not set
# CONFIG_VGA_ARB is not set
# CONFIG_AUDITSYSCALL is not set
# CONFIG_CHECKPOINT_RESTORE is not set
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
#. Saves about 17K, and none of the quirks are likely to be needed
# CONFIG_PCI_QUIRKS is not set
# CONFIG_FTRACE is not set
# CONFIG_KSM is not set
CONFIG_IPV6=m
# CONFIG_NET_MPLS_GSO is not set
# CONFIG_NETLINK_MMAP is not set
# CONFIG_SECURITY_YAMA is not set
# CONFIG_RD_LZ4 is not set

For ixp4xx we have these as well:

#. Saves about 5K
# CONFIG_USER_NS is not set
#. Saves about 7K
# CONFIG_MEMCG is not set
#. Saves about 3K
# CONFIG_BPF_JIT is not set

(I think the built-in drivers for ixp4xx are smaller as well.)

Ben.

-- 
Ben Hutchings
A free society is one where it is safe to be unpopular. - Adlai Stevenson
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