Date: Fri, 12 Jul 2013 16:50:41 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-acpi@freebsd.org Cc: Rohit Athavale <rathaval@uci.edu> Subject: Re: ACPI MADT BSP Details Message-ID: <201307121650.41701.jhb@freebsd.org> In-Reply-To: <CAN5OPshTnQ-SNhDBe=9Q4iD00FyWd0PPeaGzt_tybG8dMbpAQQ@mail.gmail.com> References: <CAN5OPshTnQ-SNhDBe=9Q4iD00FyWd0PPeaGzt_tybG8dMbpAQQ@mail.gmail.com>
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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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