[PATCH][Newlib][AArch32] Add support for HLT to Mixed Mode models

[Tamar Christina]

Hi Corinna,

So sorry, I had been busy sending patches all day and forgot about the different
format for newlib.

I have updated my scripts to generate git format patches for newlib so it
shouldn't happen again!

Ok for master?

Thanks,
Tamar

The 02/07/2019 19:26, Corinna Vinschen wrote:
> On Feb  7 16:05, Tamar Christina wrote:
> > Hi All,
> > 
> > The Semihosting v2 protocol requires us to output the Armv8-a HLT instruction
> > when in mixed mode (SEMIHOST_V2_MIXED_MODE), however it also requires this to
> > be done for Armv7-a and earlier architectures.
> > 
> > The HLT instruction is defined in the undefined encoding space for older
> > architectures but simulators such as QEMU already trap on it [1] for all
> > architectures and is a requirement for semihosting v2 [2]
> > 
> > Unfortunately the GAS restricts the use of HLT to Armv8-a which requires us to
> > use the instruction encodings we want directly in crt0.
> > 
> > This patch does this, I have not updated newlib/libc/* as that is quite out of
> > date already.  A proper sync is needed in order to get things back in sync.
> > 
> > A different patch for this would be best.
> > 
> > [1] https://github.com/qemu/qemu/commit/19a6e31c9d2701ef648b70ddcfc3bf64cec8c37e
> > [2] https://developer.arm.com/docs/100863/latest/the-semihosting-interface
> > 
> > Regtested on arm-none-eabi and no issues.
> > 
> > Ok for trunk?
> 
> Sorry, no.
> 
> > Thanks,
> > Tamar
> > 
> > libgloss/ChangeLog:
> > 
> > 2019-02-07  Tamar Christina  <tamar.christina@arm.com>
> > 
> > 	PR libgloss/24070
> > 	* arm/crt0.S: Convert macros to function Macros.
> > 	* arm/swi.h (AngelSWI_ARM, AngelSWI): Use raw insn encoding for
> > 	SEMIHOST_V2_MIXED_MODE case.
> > 	(AngelSWIAsm): Make function.
> > 	(AngelSWIInsn, AngelSWIAsm): Use .inst directive as instruction.
> 
> Did you have a look into libgloss/ChangeLog lately?  We're using git for
> three years now.  Please provide patches in git format-patch format and
> provide a normal git log entry explaining what the patch does and why.
> We don't do CVS ChangeLogs anymore.
> 
> 
> Thanks,
> Corinna
> 
> -- 
> Corinna Vinschen
> Cygwin Maintainer
> Red Hat



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