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From: Jung-uk Kim <jkim@FreeBSD.org>
To: John Baldwin <jhb@freebsd.org>
Date: Mon, 14 Feb 2011 13:58:44 -0500
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Cc: freebsd-current@freebsd.org, Matthew Fleming <mdf356@gmail.com>
Subject: Re: acpi_resource bug?
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On Monday 14 February 2011 01:37 pm, John Baldwin wrote:
> On Monday, February 14, 2011 1:30:18 pm Jung-uk Kim wrote:
> > On Monday 14 February 2011 10:29 am, Matthew Fleming wrote:
> > > On Mon, Feb 14, 2011 at 6:24 AM, John Baldwin <jhb@freebsd.org>
> >
> > wrote:
> > > > On Sunday, February 13, 2011 2:46:07 pm Matthew Fleming wrote:
> > > >> I'm not very familiar with the acpi code, but we have seen
> > > >> an intermittent issue on boot:
> > > >>
> > > >> 1) should the length of the bcopy() be changed to either
> > > >> respect res->Length or the actual length of the
> > > >> ACPI_RESOURCE_DATA for the type?
> > > >
> > > > It should just use res->Length:
> > >
> > > Is there a guarantee that res->Length is <=
> > > sizeof(ACPI_RESOURCE) ?
> >
> > No.  Please try the attached patch (after your r218685).
>
> I think your patch is correct, but are you saying that ACPICA will
> return a resource with a size that doesn't match its type?
>
> ACPI_RESOURCE_DATA is a union of all the various resource types,
> and it does contain both ACPI_RESOURCE_IRQ and
> ACPI_RESOURCE_EXTENDED_IRQ, so it's hard to see how res->Length
> would be greater than the size of ACPI_RESOURCE.

Some resource type has variable size.  For example, 
ACPI_RESOURCE_EXTENDED_IRQ has ACPI_RESOURCE_SOURCE field, which has 
a pointer to string and Length field will include length of the 
string (+ 1 for null terminator).  Also, the Length only includes the 
ACPI_RESOURCE_DATA, not the header itself, etc.

Jung-uk Kim