This patch uses do_cpuid function to fetch CPU Physical and Virtual address sizes and adds 2 new sysctl machine dependant OIDs (machdep.cpu_physical_address_bits and machdep.cpu_virtual_address_bits).
In order to retrieve the information, it calls do_cpuid by setting eax register to 0x80000008 value like referenced in chapter 5.2.7 in the CPUID specification [1] Apple, Inc. in xnu kernel do the same thing but they created a specific node called 'machdep.cpu' to store CPU Vendor information, the sysctls are machdep.cpu.address_bits.virtual and machdep.cpu.address_bits.virtual. I really would like to see this patch in our operating system because it's a valuable information nowdays and should be provided like others. Thus, I would like advices to see if before to be imported it needs modification to fit like Apple (i.e using a new sysctl node) or stay like that. Also, I profited of this changes to patch sys/modules/linprocfs in order to display the address sizes values in the output of /usr/compat/linux/proc/cpuinfo like it's done in Linux procfs [2]. I filled a pr referenced as amd64/178357 [3]. My kernel was rebuilt without any problems in r250287 and it works as expected. You could find details here [4] and patch in attachment. Regards [1] http://www.intel.com/content/dam/www/public/us/en/documents/application-notes/processor-identification-cpuid-instruction-note.pdf [2] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kernel/cpu/proc.c#n113 [3] http://www.freebsd.org/cgi/query-pr.cgi?pr=178357 [4] http://people.freebsd.org/~sbz/cpu/ -- Sofian Brabez
Index: amd64/amd64/identcpu.c
===================================================================
--- amd64/amd64/identcpu.c (revision 250287)
+++ amd64/amd64/identcpu.c (working copy)
@@ -109,6 +109,12 @@
SYSCTL_INT(_hw, OID_AUTO, clockrate, CTLFLAG_RD,
&hw_clockrate, 0, "CPU instruction clock rate");
+SYSCTL_UINT(_machdep, OID_AUTO, cpu_physical_address_bits, CTLFLAG_RD,
+ &cpu_pma_bits, 0, "CPU physical address bits");
+
+SYSCTL_UINT(_machdep, OID_AUTO, cpu_virtual_address_bits, CTLFLAG_RD,
+ &cpu_vma_bits, 0, "CPU virtual address bits");
+
static eventhandler_tag tsc_post_tag;
static char cpu_brand[48];
@@ -516,6 +522,16 @@
cpu_feature = regs[3];
cpu_feature2 = regs[2];
+ /* Intel CPUID Specification chapter 5.2.7
+ * eax=0x80000008
+ * */
+ do_cpuid(0x80000008, regs);
+
+ /* upper bits are virtual size */
+ cpu_vma_bits = ((regs[0] >> 8) & 0xFF);
+ /* lower bits are physical size */
+ cpu_pma_bits = (regs[0] & 0xFF);
+
/*
* Clear "Limit CPUID Maxval" bit and get the largest standard CPUID
* function number again if it is set from BIOS. It is necessary
Index: amd64/amd64/initcpu.c
===================================================================
--- amd64/amd64/initcpu.c (revision 250287)
+++ amd64/amd64/initcpu.c (working copy)
@@ -66,10 +66,12 @@
u_int cpu_high; /* Highest arg to CPUID */
u_int cpu_exthigh; /* Highest arg to extended CPUID */
u_int cpu_id; /* Stepping ID */
+u_int cpu_pma_bits; /* CPU physical address bits */
u_int cpu_procinfo; /* HyperThreading Info / Brand Index / CLFUSH */
u_int cpu_procinfo2; /* Multicore info */
char cpu_vendor[20]; /* CPU Origin code */
u_int cpu_vendor_id; /* CPU vendor ID */
+u_int cpu_vma_bits; /* CPU virtual address bits */
u_int cpu_fxsr; /* SSE enabled */
u_int cpu_mxcsr_mask; /* Valid bits in mxcsr */
u_int cpu_clflush_line_size = 32;
Index: amd64/include/md_var.h
===================================================================
--- amd64/include/md_var.h (revision 250287)
+++ amd64/include/md_var.h (working copy)
@@ -54,10 +54,12 @@
extern u_int cpu_id;
extern u_int cpu_max_ext_state_size;
extern u_int cpu_mxcsr_mask;
+extern u_int cpu_pma_bits;
extern u_int cpu_procinfo;
extern u_int cpu_procinfo2;
extern char cpu_vendor[];
extern u_int cpu_vendor_id;
+extern u_int cpu_vma_bits;
extern char ctx_switch_xsave[];
extern char kstack[];
extern char sigcode[];
Index: compat/linprocfs/linprocfs.c
===================================================================
--- compat/linprocfs/linprocfs.c (revision 250287)
+++ compat/linprocfs/linprocfs.c (working copy)
@@ -310,6 +310,12 @@
fqmhz, fqkhz, fqmhz, fqkhz);
}
+ if (cpu_vma_bits != 0 && cpu_vma_bits != 0) {
+ sbuf_printf(sb,
+ "address sizes\t: %u bits physical, %u bits virtual\n",
+ cpu_pma_bits, cpu_vma_bits);
+ }
+
return (0);
}
#endif /* __i386__ || __amd64__ */
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