Date: Fri, 12 Jul 2013 14:10:36 -0700 From: Rohit Athavale <rathaval@uci.edu> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-acpi@freebsd.org Subject: Re: ACPI MADT BSP Details Message-ID: <CAN5OPshdLZysBMDi%2BNH-NSNi9AH3rS6BZRq4=0KkX01H88KCng@mail.gmail.com> In-Reply-To: <201307121650.41701.jhb@freebsd.org> References: <CAN5OPshTnQ-SNhDBe=9Q4iD00FyWd0PPeaGzt_tybG8dMbpAQQ@mail.gmail.com> <201307121650.41701.jhb@freebsd.org>
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Thanks John. After reading into details of the ACPI spec, it is also said in the spec that the first processor APIC entry also happens to be the BSP . It is expected the BSP always be kept the first entry in processor APIC's. Best Regards, Rohit *A*thavale On Fri, Jul 12, 2013 at 1:50 PM, John Baldwin <jhb@freebsd.org> wrote: > On Wednesday, July 10, 2013 7:48:42 pm Rohit Athavale wrote: > > Hi Folks, > > > > I have two questions about discovering the processors from the MADT > table. > > > > Firstly, > > Can we find out which processor is the BSP from the MADT tables? > > When comparing the userland mptable binary's output versus acpidump's > > output I noticed that mptable informs us about which processor is the BSP > > and which are AP's . > > However I did not see this in the MADT tables. > > Is there a way to find out which processor is the BSP by means of any of > > the ACPI tables. > > Nope. You can read the local APIC ID of the current CPU during your > bootstrap > though. > > > Secondly, > > Can we write into /dev/mem to say update the contents of MPTable with > > values that are non -default. I plan to read some values from the ACPI > > tables and update the MP tables. > > Is the /dev/mem/ file composed of physical addresses for user space > memory > > ? I know this may not qualify as the correct place to ask,but I guess > acpi > > list might have an answer to this. > > Yes, you can likely do this. > > -- > John Baldwin >
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