[PATCH 3/3] ARM: early_printk: use printascii() rather than printch()

[Nicolas Pitre]

On Thu, 2 Nov 2017, Chris Brandt wrote:

> Oops, I meant to show this:
> 
> $ arm-linux-gnueabihf-as -version
> GNU assembler (Linaro_Binutils-2017.01) 2.25.2 Linaro 2016_02
> Copyright (C) 2014 Free Software Foundation, Inc.
> This program is free software; you may redistribute it under the terms of
> the GNU General Public License version 3 or later.
> This program has absolutely no warranty.
> This assembler was configured for a target of `arm-linux-gnueabihf'.

This is very strange. Here's a quick test with all the binutils versions 
I have lying around on my system:

$ echo -e "mov r0, #'\\\r'\nmov r1, '\\\r'"
mov r0, #'\r'
mov r1, '\r'
$ echo -e "mov r0, #'\\\r'\nmov r1, '\\\r'" > /tmp/t.s
$ for as in $(find /opt -name arm-linux-\*-as); do \
> $as --version | head -1; \
> $as /tmp/t.s -o /tmp/t.o; done
GNU assembler (Linaro_Binutils-2017.05) 2.27.0.20161019
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'
GNU assembler (crosstool-NG linaro-1.13.1-4.7-2013.02-01-20130221 - Linaro GCC 2013.02) 2.23.1
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'
GNU assembler (Linaro_Binutils-2017.05) 2.25.2 Linaro 2016_02
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'
GNU assembler (crosstool-NG linaro-1.13.1-4.9-2014.09 - Linaro GCC 4.9-2014.09) 2.24.0.20140829 Linaro 2014.09
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'
GNU assembler (GNU Binutils) Linaro 2014.11-3-git 2.24.0.20141017
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'
GNU assembler (Linaro_Binutils-2017.08) 2.28.2.20170706
/tmp/t.s: Assembler messages:
/tmp/t.s:2: Error: immediate expression requires a # prefix -- `mov r1,13'

They all fail, including the version that looks like the one you have.

Could you try that little test above on your side?

> > So, as far as ARM assembly in the Linux kernel goes, all constants must
> > be preceded by # whether or not binutils requires it - no exceptions.
> > Please always test assembly changes with a binutils version that is not
> > gratuitously broken!
> 
> Somewhat ironic since Nicolas works for Linaro.

I'm not involved with the toolchain people though, other than using 
their output.


Nicolas