Re: [coreboot] [coreinfo] [PATCH] fix cpu flags overwrite

[Ulf Jordan]

Hello Stefan,

On Fri, 26 Sep 2008, Stefan Reinauer wrote:
> Hi Ulf,

Ulf Jordan wrote:
> > Index: coreinfo/cpuinfo_module.c
> >
> > --- coreinfo/cpuinfo_module.c   (revision 3569)
> > +++ coreinfo/cpuinfo_module.c   (working copy)
> > @@ -97,6 +97,7 @@
> >  {
> >         int i;
> >         int lrow = *row;
> >   int output_available=0;
> >
> >   wmove(win, lrow, 2);
> >
> > @@ -104,8 +105,10 @@
> >                 if (flags[i] == NULL)
> >                         continue;
> >           if (reg & (1 << i))
> >           if (reg & (1 << i)) {
> >                   wprintw(win, "%s ", flags[i]);
> >                   output_available=1;
> >           }
> >
> >           if (i && (i % 16) == 0) {
> >                   lrow++;
> >
> > @@ -113,6 +116,8 @@
> >                 }
> >         }
> >   lrow += output_available;
> >   *row = lrow;
> >
> > }
> >
> > @@ -131,7 +136,7 @@
> >     switch (vendor) {
> >     case VENDOR_AMD:
> >           wmove(win, lrow++, 1);
> >           wmove(win, lrow, 1);
> >           wprintw(win, "AMD Extended Flags: ");
>
> This hunk will make the decoded flags overwrite the heading, please
> remove.

In which case would that happen? The   lrow += output_available; part
above prevents this on my system. Does it not work as intended on your
machine?

lrow += output_available; makes certain that there is space *after* 
already written flags, but this is another issue.

By removing the ++, the extended flags are written onto the "Intel 
Extended Flags:/AMD Extended Flags:" heading, starting in position three. 
I've tested in QEMU, and the result is as follows.

Without patch:
  Features:
   fpu de pse tsc msr pae mce cx8 apic sep pge cmov pat
   mmx fxsr sse sse2
  Intel Extended Flags:
   sse3

With patch:
  Features:
   fpu de pse tsc msr pae mce cx8 apic sep pge cmov pat
   mmx fxsr sse sse2

Isse3 Extended Flags:

With patch, excluding last two hunks:
  Features:
   fpu de pse tsc msr pae mce cx8 apic sep pge cmov pat
   mmx fxsr sse sse2

Intel Extended Flags:
   sse3

The reason for overwriting when ++ is removed is that wmove positions the 
cursor at current lrow and wprintw prints the heading. Directly 
afterwards, decode_flags starts writing the decode flags at lrow 
(unchanged), but at x = 2.

This is the reason I suggested the patch to be applied, except for the 
last two hunks.

Regards,

Ulf