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Re: [PATCH] Provide a stub ioperm implementation for ARMv5 and later
- From: Phil Blundell <pb at pbcl dot net>
- To: Aurelien Jarno <aurelien at aurel32 dot net>
- Cc: libc-alpha at sourceware dot org
- Date: Sat, 12 Dec 2015 20:26:27 +0000
- Subject: Re: [PATCH] Provide a stub ioperm implementation for ARMv5 and later
- Authentication-results: sourceware.org; auth=none
- References: <1449946774-18072-1-git-send-email-aurelien at aurel32 dot net>
On Sat, 2015-12-12 at 19:59 +0100, Aurelien Jarno wrote:
> The ioperm, iopl, in{b,w,l} and out{b,w,l} functions only make sense
> on ARMv4.
This statement isn't strictly true. There is no inherent relationship
between the architecture level and the availability or not of the
port-mapped I/O functions. And, in fact, a quick survey suggests that
there is at least one counterexample in the kernel: CONFIG_ARCH_VIPER is
a PXA25x board (hence ARMv5TE) and seems to include ISA. So, I am not
all that keen on this patch.
If you wanted to clean up the ioperm code a bit then it would probably
make sense to remove all the legacy stuff that grubs around
in /proc/cpuinfo and /etc/arm_systype to figure out what sort of machine
it's on, since this is only needed for kernels that are so old as to
lack the CTL_BUS_ISA sysctls.
p.