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

[Nicolas Pitre]

On Thu, 2 Nov 2017, Nicolas Pitre wrote:

> Would be good to figure out what option makes it accept no # and see if 
> that can be avoided for kernel build.

OK.. I wanted to get to the bottom of this. The gas documentation says:

|9.4.2.1 Instruction Set Syntax
|..............................
|
|Two slightly different syntaxes are supported for ARM and THUMB
|instructions.  The default, `divided', uses the old style where ARM and
|THUMB instructions had their own, separate syntaxes.  The new,
|`unified' syntax, which can be selected via the `.syntax' directive,
|and has the following main features:
|
|   * Immediate operands do not require a `#' prefix.
|
|   * The `IT' instruction may appear, and if it does it is validated
|     against subsequent conditional affixes.  In ARM mode it does not
|     generate machine code, in THUMB mode it does.
|
|   * For ARM instructions the conditional affixes always appear at the
|     end of the instruction.  For THUMB instructions conditional
|     affixes can be used, but only inside the scope of an `IT'
|     instruction.
|
|   * All of the instructions new to the V6T2 architecture (and later)
|     are available.  (Only a few such instructions can be written in the
|     `divided' syntax).
|
|   * The `.N' and `.W' suffixes are recognized and honored.
|
|   * All instructions set the flags if and only if they have an `s'
|     affix.

So this is a mixed bag of features and, unless I'm missing something, 
there is no way to get some and not the others. And we do need most of 
those features for Thumb2 kernel build.


Nicolas