Re: [PATCH][2.4.23-pre3] repair mpparse for default MP systems

[Mikael Pettersson <mikpe@csd.uu.se>]

Mathieu Desnoyers writes:
 > * Mikael Pettersson (mikpe@csd.uu.se) wrote:
 > > Mathieu,
 > > 
 > > This patch for 2.4.23-pre3 should fix the problems your dual
 > > P5 with default MP config has been having since 2.4.21-pre2.
 > > Please let us know if it works or not.
 > > 
 > > /Mikael
 > > 
 > 
 > Yes, I just tested this patch, and everything seems to work fine. Thank
 > you. :)
 > 
 > The only point I see, which is not triggered on my machine (because of
 > the absence of ACPI) is this one :
 > 
 > There is also an initialization of this mp_irqs variable in
 > mp_config_acpi_legacy_irqs from mpparse.c. It only seems to be called
 > from within acpi_boot_init in acpi.c. So I wonder if it's possible that
 > we do use default configuration and then also go into
 > mp_config_acpi_legacy_irqs during the acpi init, thus reserving the
 > memory twice and forgetting the old pointer, which could lead to an
 > erratic result.
 > 
 > If it's possible, then there is still a problem in there.

I looked through acpi/mpparse/setup and I don't think there is
a problem. acpi does mp_config_acpi_legacy_irqs if it found its
tables, but this is done before get_smp_config, and get_smp_config
bails out early if ACPI already has done the deed. If it were a
problem, it would affect _all_ MP configs not just yours.

I'll submit the patch to Marcelo then, with appropriate explaination.
(No forward port to 2.6 is needed, since the arrays-to-pointers
change hasn't been done there (yet).)

/Mikael