Bob,
Wouldn't it be less confusing if the dis-assembler
also adding the trailing underscores to match what
is actually done by the interpreter?
thanks,
-Len
On Wednesday 26 March 2008, Moore, Robert wrote:
> References, ACPI specification 3.0b:
>
>
> 5.3 ACPI Namespace
>
> By convention, when an ASL compiler pads a name shorter than 4
> characters, it is done so with trailing underscores ('_'). See the
> language definition for AML NameSeg in Section 16, "ACPI Source Language
> Reference."
>
> (Reference should point to section 18, AML reference)
>
>
>
> 18.2.2 Name Objects Encoding
>
> NameSeg := <LeadNameChar NameChar NameChar NameChar>
> // Notice that NameSegs shorter than 4 characters are filled with
> // trailing underscores ('_'s).
>
>
>
>
>
> -----Original Message-----
> From: Moore, Robert
> Sent: Wednesday, March 26, 2008 6:59 PM
> To: 'Len Brown'
> Cc: 'aystarik@xxxxxxxxx'; Lin, Ming M
> Subject: RE: Re: ISA -> ISA_ (Re: [GIT PATCH] ACPI patches for
> 2.6.25-rc6)
>
> Whenever an ACPI namepath is parsed (each 4 character name within a
> namepath is called a "nameseg"), each nameseg is padded out with
> underscores if it is shorter than 4 characters. This happens whenever a
> named object is created and whenever a reference to a name is
> encountered.
>
> Thus, internally, ALL namesegs are exactly 4 characters, no need to add
> code to handle variable-length namesegs.
>
> Thus, smaller code and fewer bugs. This is also mentioned in the ACPI
> spec somewhere.
>
> Bob
>
>
> Example:
>
> Name (I, 0x1234)
>
> Will be entered into the namespace as
>
> I___
>
> A reference to I such as
>
> Store (\DEV0\I, Local0)
>
> Will convert "I" to "I___" during AML parsing.
>
>
>
> -----Original Message-----
> From: Len Brown [mailto:lenb@xxxxxxxxxx]
> Sent: Wednesday, March 26, 2008 11:00 AM
> To: Moore, Robert
> Subject: Fwd: Re: ISA -> ISA_ (Re: [GIT PATCH] ACPI patches for
> 2.6.25-rc6)
>
> Bob,
> can you comment on this thread?
>
> thanks,
> -Len
>
> ---------- Forwarded Message ----------
>
> Subject: Re: ISA -> ISA_ (Re: [GIT PATCH] ACPI patches for 2.6.25-rc6)
> Date: Wednesday 26 March 2008
> From: Alexey Starikovskiy < aystarik@xxxxxxxxx >
> To: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
>
> Bjorn Helgaas wrote:
> > I'm curious about how this works. I disassembled the DSDT from
> > http://bugzilla.kernel.org/show_bug.cgi?id=4773 (I attached the
> disassembly
> > at http://bugzilla.kernel.org/attachment.cgi?id=15448&action=view),
> and
> > the _PRT contains "_SB" and "ISA" (no trailing underscores):
> >
> > Package (0x04)
> > {
> > 0x000DFFFF,
> > 0x00,
> > \_SB.PCI0.ISA.LNKA,
> > 0x00
> > }
> >
> > But by the time we get to acpi_pci_irq_add_entry(), we've added the
> > underscores somewhere (see
> > http://bugzilla.kernel.org/attachment.cgi?id=15423&action=view):
> >
> > 0000:00:0d[A] -> \_SB_.PCI0.ISA_.LNKA
> >
> > I don't know where this happens, but it certainly confused me, and
> > it seems like it could lead to other bugs.
> >
> ACPI is supposed to add trailing underscore for pad all names to 4
> bytes.
> So ISA will be padded to ISA_.
>
> Regards,
> Alex.
>
> -------------------------------------------------------
>
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