Re: [PATCH] target/hppa: Allow, but diagnose, LDCW aligned only mod 4

[Philippe Mathieu-Daudé]

On 1/17/20 8:23 PM, Richard Henderson wrote:
> On 1/17/20 8:50 AM, Philippe Mathieu-Daudé wrote:
> > On Fri, Jan 17, 2020 at 2:53 AM Richard Henderson
> > <address@hidden> wrote:
> > > The PA-RISC 1.1 specification says that LDCW must be aligned mod 16
> > > or the operation is undefined.  However, real hardware only generates
> > > an unaligned access trap for unaligned mod 4.
> >
> > This Linux kernel commit seems relevant:
> >
> > https://github.com/torvalds/linux/commit/14e256c107304#diff-e85862c7227599cb24e36494f75948d5R159-R164
> >
> >    /* From: "Jim Hull" <jim.hull of hp.com>
> >    I've attached a summary of the change, but basically, for PA 2.0, as
> >    long as the ",CO" (coherent operation) completer is specified, then the
> >    16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
> >    they only require "natural" alignment (4-byte for ldcw, 8-byte for
> >    ldcd). */
>
> It isn't completely relevant.  We don't implement hppa 2.0.

Oh... It was late and I misread it as:

  if (PA2)
    ...
  else
    ... "instead of PA 2.0 ... the 16-byte alignment ... is
    relaxed, and insted only require "natural" alignment ..."

  endif

> I added a TODO comment for HPPA64, as I said in reply to Dave Anglin elsewhere
> in this thread.