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

Corinna Vinschen <[email protected]> Thu, 7 Feb 2019 19:26:13 +0100

Newsgroups	gmane.comp.lib.newlib
Message-ID	<[email protected]>

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  <[email protected]>
> 
> 	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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