>> 1) Use the RSDT instead of the XSDT and automatically get the "correct" >FADT with no 64-bit register definitions. >> >> 2) Use the XSDT as is done today, but use the 32-bit values instead of >the 64-bit values in the extended FADT. What we really want to know is what does windows do, (1), or (2). >-----Original Message----- >From: Matthew Garrett [mailto:mjg59@xxxxxxxxxxxxx] >Sent: Friday, December 05, 2008 8:38 AM >To: Moore, Robert >Cc: Koornstra, Reinoud; linux-acpi@xxxxxxxxxxxxxxx; Brown, Len; Lin, Ming >M; Zhao, Yakui >Subject: Re: 2.6.28-rc7 acpi error messages > >On Fri, Dec 05, 2008 at 08:32:11AM -0800, Moore, Robert wrote: >> So, it looks like there are two possible solutions for this machine: >> >> 1) Use the RSDT instead of the XSDT and automatically get the "correct" >FADT with no 64-bit register definitions. >> >> 2) Use the XSDT as is done today, but use the 32-bit values instead of >the 64-bit values in the extended FADT. > >I think (2) is the correct answer here. If the 64-bit values use an >address space other than system io, we probably want to use the 64-bit >values, so we'll need to parse those addresses anyway. I've sent a patch >that does this to linux-acpi last week - here's another copy. > >commit acdf192e7427366b01fe37704fe95b205490dad2 >Author: Matthew Garrett <mjg@xxxxxxxxxx> >Date: Mon Dec 1 10:54:05 2008 +0000 > > Use 32-bit FADT values on X86 > > The ACPI specification says that we should use the 64-bit address >offsets > contained within the FADT if they exist. However, Windows uses the >legacy > address. Various vendors have left incorrect values in the 64-bit field > which then causes problems later. Since the vast majority of machines >have > never been tested with an OS that uses the 64-bit value by default, we >should > behave like Windows and ignore the spec by only using the 64-bit >address if > it contains something that can't be represented in the legacy field. >Since > system io space is only 16 bits on x86, this should be entirely safe. > > Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx> > >diff --git a/drivers/acpi/tables/tbfadt.c b/drivers/acpi/tables/tbfadt.c >index 2817158..89a3c82 100644 >--- a/drivers/acpi/tables/tbfadt.c >+++ b/drivers/acpi/tables/tbfadt.c >@@ -320,9 +320,30 @@ static void acpi_tb_convert_fadt(void) > ACPI_ADD_PTR(struct acpi_generic_address, >&acpi_gbl_FADT, > fadt_info_table[i].target); > >- /* Expand only if the X target is null */ >- >- if (!target->address) { >+ /* >+ * The ACPI specification says that we should use the >+ * 64-bit address offsets if they exists. However, >+ * Windows uses the legacy address. Various vendors >+ * have left incorrect values in the 64-bit field, >+ * which then causes problems later. Since the vast >+ * majority of machines have never been tested with an >+ * OS that uses the 64-bit value by default, we should >+ * behave like Windows and ignore the spec by only >+ * using the 64-bit address if it contains something >+ * that can't be represented in the legacy >+ * field. Since system io space is only 16 bits on >+ * x86, this should be entirely safe. We also extend >+ * the 32-bit value into the 64-bit one if no 64-bit >+ * address is provided. >+ */ >+ >+ if (!target->address >+#ifdef CONFIG_X86 >+ || (target->space_id == ACPI_ADR_SPACE_SYSTEM_IO && >+ *ACPI_ADD_PTR(u32, &acpi_gbl_FADT, >+ fadt_info_table[i].source)) >+#endif >+ ) { > acpi_tb_init_generic_address(target, > *ACPI_ADD_PTR(u8, > >&acpi_gbl_FADT, > >-- >Matthew Garrett | mjg59@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
