Re: [RESEND] [PATCH 2/3] Introduce acpi_root_table=rsdt boot param and dmi list to force rsdt

[Henrique de Moraes Holschuh <hmh@hmh.eng.br>]

On Mon, 20 Oct 2008, Matthew Garrett wrote:
> On Mon, Oct 20, 2008 at 03:51:24PM -0200, Henrique de Moraes Holschuh wrote:
> > On Mon, 20 Oct 2008, Matthew Garrett wrote:
> > > But *why* is Vista not showing the symptoms?
> > 
> > I very much doubt anyone ever attempted to run Vista on a R40e or a R50e.
> > It probably won't work well on the T4x/R51/R52 either, but I haven't tried.
> 
> I'd be surprised if nobody has done it. The hardware is above the 
> minimum spec.

I'd ask someone that did before I assume it worked fine (i.e. "does it
suspend and resume to RAM properly when running XP?  when running
Vista?")...

The R40e is **OLD**.  The R50e is not that newer, either.

> > > values in the table were never caught because, for some reason, Windows 
> > > never used them. The bug is that we're not using the same heuristic as 
> > > Windows. Applying a static list of hardware just results in it being 
> > > likely that we'll never fix that bug.
> > 
> > I am a bit lost, now.  Are you talking about newer ThinkPads with
> > Vista-capable BIOSes, or the older ones that can't handle it and thus are
> > only subject to some ACPI access patterns when running Linux?
> 
> The R40e and R50e have differing values in the RSDT and XSDT tables. 
> Linux uses the values from the XSDT, which apparently results in a 
> system hang whenever you attempt to perform C-state manipulation. Using 
> the RSDT values instead avoids this. Windows works fine, so is clearly 
> using the RSDT values. However, we have no knowledge of what mechanism 
> Windows uses to choose between the two sets of values.

Err... WHICH versions of Windows "work fine"?  And HOW do those versions
behave?

One cannot assume "Vista" for "Windows" on such old boxes.  You need
explicit confirmation that an user ran Vista and tried suspend/resume,
really.  Because nobody would be surprised if Vista crashed hard on a R50e,
let alone if it worked moderately right but couldn't survive a
suspend/resume cycle.  It wouldn't be "newsworthy".

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh