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Hotplug CPU Boot Change 2/2
.... And this fixes up x86.
Name: Hot-plug CPU Boot Rewrite for i386
Author: Rusty Russell
Status: Tested 2.5.25, dual SMP
Depends: Hotcpu/hotcpu-boot.patch.gz
D: This modifies the i386 boot sequence to "plug in" CPUs one at a
D: time. This is the minimal change to make it work (the CPUs are
D: brought up as normal during the "smp_prepare_cpus()" probe phase).
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/apic.c working-2.5.25-hotcpu/arch/i386/kernel/apic.c
--- linux-2.5.25/arch/i386/kernel/apic.c Thu Jun 20 01:28:47 2002
+++ working-2.5.25-hotcpu/arch/i386/kernel/apic.c Mon Jul 15 18:23:12 2002
@@ -798,9 +798,9 @@
apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
}
-void setup_APIC_timer(void * data)
+static void setup_APIC_timer(unsigned int clocks)
{
- unsigned int clocks = (unsigned int) data, slice, t0, t1;
+ unsigned int slice, t0, t1;
unsigned long flags;
int delta;
@@ -926,7 +926,7 @@
int dont_use_local_apic_timer __initdata = 0;
-void __init setup_APIC_clocks (void)
+void __init setup_boot_APIC_clock(void)
{
/* Disabled by DMI scan or kernel option? */
if (dont_use_local_apic_timer)
@@ -941,12 +941,16 @@
/*
* Now set up the timer for real.
*/
- setup_APIC_timer((void *)calibration_result);
+ setup_APIC_timer(calibration_result);
__sti();
+}
- /* and update all other cpus */
- smp_call_function(setup_APIC_timer, (void *)calibration_result, 1, 1);
+void __init setup_secondary_APIC_clock(void)
+{
+ __cli(); /* FIXME: Do we need this? --RR */
+ setup_APIC_timer(calibration_result);
+ __sti();
}
void __init disable_APIC_timer(void)
@@ -1178,7 +1182,7 @@
if (!skip_ioapic_setup && nr_ioapics)
setup_IO_APIC();
#endif
- setup_APIC_clocks();
+ setup_boot_APIC_clock();
return 0;
}
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/apm.c working-2.5.25-hotcpu/arch/i386/kernel/apm.c
--- linux-2.5.25/arch/i386/kernel/apm.c Sun Jul 7 02:12:17 2002
+++ working-2.5.25-hotcpu/arch/i386/kernel/apm.c Mon Jul 15 14:42:18 2002
@@ -1587,7 +1587,7 @@
p = buf;
- if ((num_online_cpus() == 1) &&
+ if ((num_possible_cpus() == 1) &&
!(error = apm_get_power_status(&bx, &cx, &dx))) {
ac_line_status = (bx >> 8) & 0xff;
battery_status = bx & 0xff;
@@ -1718,7 +1718,7 @@
}
}
- if (debug && (num_online_cpus() == 1)) {
+ if (debug && (num_possible_cpus() == 1)) {
error = apm_get_power_status(&bx, &cx, &dx);
if (error)
printk(KERN_INFO "apm: power status not available\n");
@@ -1762,7 +1762,7 @@
pm_power_off = apm_power_off;
register_sysrq_key('o', &sysrq_poweroff_op);
- if (num_online_cpus() == 1) {
+ if (num_possible_cpus() == 1) {
#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
console_blank_hook = apm_console_blank;
#endif
@@ -1905,9 +1905,7 @@
printk(KERN_NOTICE "apm: disabled on user request.\n");
return -ENODEV;
}
- /* FIXME: When boot code changes, this will need to be
- deactivated when/if a CPU comes up --RR */
- if ((num_online_cpus() > 1) && !power_off) {
+ if ((num_possible_cpus() > 1) && !power_off) {
printk(KERN_NOTICE "apm: disabled - APM is not SMP safe.\n");
return -ENODEV;
}
@@ -1961,9 +1959,7 @@
kernel_thread(apm, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND | SIGCHLD);
- /* FIXME: When boot code changes, this will need to be
- deactivated when/if a CPU comes up --RR */
- if (num_online_cpus() > 1) {
+ if (num_possible_cpus() > 1) {
printk(KERN_NOTICE
"apm: disabled - APM is not SMP safe (power off active).\n");
return 0;
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/mtrr.c working-2.5.25-hotcpu/arch/i386/kernel/mtrr.c
--- linux-2.5.25/arch/i386/kernel/mtrr.c Thu Jun 20 01:28:47 2002
+++ working-2.5.25-hotcpu/arch/i386/kernel/mtrr.c Mon Jul 15 14:42:42 2002
@@ -1055,7 +1055,7 @@
wait_barrier_cache_disable = TRUE;
wait_barrier_execute = TRUE;
wait_barrier_cache_enable = TRUE;
- atomic_set (&undone_count, num_online_cpus() - 1);
+ atomic_set (&undone_count, num_booting_cpus() - 1);
/* Start the ball rolling on other CPUs */
if (smp_call_function (ipi_handler, &data, 1, 0) != 0)
panic ("mtrr: timed out waiting for other CPUs\n");
@@ -1064,14 +1064,14 @@
/* Wait for all other CPUs to flush and disable their caches */
while (atomic_read (&undone_count) > 0) { rep_nop(); barrier(); }
/* Set up for completion wait and then release other CPUs to change MTRRs*/
- atomic_set (&undone_count, num_online_cpus() - 1);
+ atomic_set (&undone_count, num_booting_cpus() - 1);
wait_barrier_cache_disable = FALSE;
set_mtrr_cache_disable (&ctxt);
/* Wait for all other CPUs to flush and disable their caches */
while (atomic_read (&undone_count) > 0) { rep_nop(); barrier(); }
/* Set up for completion wait and then release other CPUs to change MTRRs*/
- atomic_set (&undone_count, num_online_cpus() - 1);
+ atomic_set (&undone_count, num_booting_cpus() - 1);
wait_barrier_execute = FALSE;
(*set_mtrr_up) (reg, base, size, type, FALSE);
/* Now wait for other CPUs to complete the function */
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/nmi.c working-2.5.25-hotcpu/arch/i386/kernel/nmi.c
--- linux-2.5.25/arch/i386/kernel/nmi.c Thu Jun 20 01:28:47 2002
+++ working-2.5.25-hotcpu/arch/i386/kernel/nmi.c Mon Jul 15 15:30:34 2002
@@ -81,6 +81,8 @@
sti();
mdelay((10*1000)/nmi_hz); // wait 10 ticks
+ /* FIXME: Only boot CPU is online at this stage. Check CPUs
+ as they come up. */
for (cpu = 0; cpu < NR_CPUS; cpu++) {
if (!cpu_online(cpu))
continue;
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/arch/i386/kernel/smpboot.c working-2.5.25-hotcpu/arch/i386/kernel/smpboot.c
--- linux-2.5.25/arch/i386/kernel/smpboot.c Fri Jun 21 09:41:52 2002
+++ working-2.5.25-hotcpu/arch/i386/kernel/smpboot.c Mon Jul 15 17:44:05 2002
@@ -31,7 +31,7 @@
* Maciej W. Rozycki : Bits for genuine 82489DX APICs
* Martin J. Bligh : Added support for multi-quad systems
* Dave Jones : Report invalid combinations of Athlon CPUs.
- */
+* Rusty Russell : Hacked into shape for new "hotplug" boot process. */
#include <linux/config.h>
#include <linux/init.h>
@@ -53,9 +53,6 @@
/* Set if we find a B stepping CPU */
static int __initdata smp_b_stepping;
-/* Setup configured maximum number of CPUs to activate */
-static int __initdata max_cpus = NR_CPUS;
-
/* Number of siblings per CPU package */
int smp_num_siblings = 1;
int __initdata phys_proc_id[NR_CPUS]; /* Package ID of each logical CPU */
@@ -64,7 +61,8 @@
unsigned long cpu_online_map;
static volatile unsigned long cpu_callin_map;
-static volatile unsigned long cpu_callout_map;
+volatile unsigned long cpu_callout_map;
+static unsigned long smp_commenced_mask;
/* Per CPU bogomips and other parameters */
struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned;
@@ -73,33 +71,6 @@
int smp_threads_ready;
/*
- * Setup routine for controlling SMP activation
- *
- * Command-line option of "nosmp" or "maxcpus=0" will disable SMP
- * activation entirely (the MPS table probe still happens, though).
- *
- * Command-line option of "maxcpus=<NUM>", where <NUM> is an integer
- * greater than 0, limits the maximum number of CPUs activated in
- * SMP mode to <NUM>.
- */
-
-static int __init nosmp(char *str)
-{
- max_cpus = 0;
- return 1;
-}
-
-__setup("nosmp", nosmp);
-
-static int __init maxcpus(char *str)
-{
- get_option(&str, &max_cpus);
- return 1;
-}
-
-__setup("maxcpus=", maxcpus);
-
-/*
* Trampoline 80x86 program as an array.
*/
@@ -139,7 +110,7 @@
* a given CPU
*/
-void __init smp_store_cpu_info(int id)
+static void __init smp_store_cpu_info(int id)
{
struct cpuinfo_x86 *c = cpu_data + id;
@@ -193,29 +164,6 @@
}
/*
- * Architecture specific routine called by the kernel just before init is
- * fired off. This allows the BP to have everything in order [we hope].
- * At the end of this all the APs will hit the system scheduling and off
- * we go. Each AP will load the system gdt's and jump through the kernel
- * init into idle(). At this point the scheduler will one day take over
- * and give them jobs to do. smp_callin is a standard routine
- * we use to track CPUs as they power up.
- */
-
-static atomic_t smp_commenced = ATOMIC_INIT(0);
-
-void __init smp_commence(void)
-{
- /*
- * Lets the callins below out of their loop.
- */
- Dprintk("Setting commenced=1, go go go\n");
-
- wmb();
- atomic_set(&smp_commenced,1);
-}
-
-/*
* TSC synchronization.
*
* We first check wether all CPUs have their TSC's synchronized,
@@ -268,7 +216,7 @@
unsigned long one_usec;
int buggy = 0;
- printk("checking TSC synchronization across CPUs: ");
+ printk("checking TSC synchronization across %u CPUs: ", num_booting_cpus());
one_usec = ((1<<30)/fast_gettimeoffset_quotient)*(1<<2);
@@ -289,7 +237,7 @@
/*
* all APs synchronize but they loop on '== num_cpus'
*/
- while (atomic_read(&tsc_count_start) != num_online_cpus()-1)
+ while (atomic_read(&tsc_count_start) != num_booting_cpus()-1)
mb();
atomic_set(&tsc_count_stop, 0);
wmb();
@@ -308,7 +256,7 @@
/*
* Wait for all APs to leave the synchronization point:
*/
- while (atomic_read(&tsc_count_stop) != num_online_cpus()-1)
+ while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1)
mb();
atomic_set(&tsc_count_start, 0);
wmb();
@@ -317,16 +265,16 @@
sum = 0;
for (i = 0; i < NR_CPUS; i++) {
- if (cpu_online(i)) {
+ if (test_bit(i, &cpu_callout_map)) {
t0 = tsc_values[i];
sum += t0;
}
}
- avg = div64(sum, num_online_cpus());
+ avg = div64(sum, num_booting_cpus());
sum = 0;
for (i = 0; i < NR_CPUS; i++) {
- if (!cpu_online(i))
+ if (!test_bit(i, &cpu_callout_map))
continue;
delta = tsc_values[i] - avg;
if (delta < 0)
@@ -359,7 +307,7 @@
int i;
/*
- * num_online_cpus is not necessarily known at the time
+ * Not every cpu is online at the time
* this gets called, so we first wait for the BP to
* finish SMP initialization:
*/
@@ -367,7 +315,7 @@
for (i = 0; i < NR_LOOPS; i++) {
atomic_inc(&tsc_count_start);
- while (atomic_read(&tsc_count_start) != num_online_cpus())
+ while (atomic_read(&tsc_count_start) != num_booting_cpus())
mb();
rdtscll(tsc_values[smp_processor_id()]);
@@ -375,7 +323,7 @@
write_tsc(0, 0);
atomic_inc(&tsc_count_stop);
- while (atomic_read(&tsc_count_stop) != num_online_cpus()) mb();
+ while (atomic_read(&tsc_count_stop) != num_booting_cpus()) mb();
}
}
#undef NR_LOOPS
@@ -403,7 +351,7 @@
*/
phys_id = GET_APIC_ID(apic_read(APIC_ID));
cpuid = smp_processor_id();
- if (test_and_set_bit(cpuid, &cpu_online_map)) {
+ if (test_bit(cpuid, &cpu_callin_map)) {
printk("huh, phys CPU#%d, CPU#%d already present??\n",
phys_id, cpuid);
BUG();
@@ -501,15 +449,17 @@
*/
cpu_init();
smp_callin();
- while (!atomic_read(&smp_commenced))
+ while (!test_bit(smp_processor_id(), &smp_commenced_mask))
rep_nop();
+ setup_secondary_APIC_clock();
enable_APIC_timer();
/*
* low-memory mappings have been cleared, flush them from
* the local TLBs too.
*/
local_flush_tlb();
-
+ set_bit(smp_processor_id(), &cpu_online_map);
+ wmb();
return cpu_idle();
}
@@ -943,7 +893,6 @@
unmap_cpu_to_boot_apicid(cpu, apicid);
clear_bit(cpu, &cpu_callout_map); /* was set here (do_boot_cpu()) */
clear_bit(cpu, &cpu_initialized); /* was set by cpu_init() */
- clear_bit(cpu, &cpu_online_map); /* was set in smp_callin() */
cpucount--;
}
@@ -1015,7 +964,7 @@
int cpu_sibling_map[NR_CPUS] __cacheline_aligned;
-void __init smp_boot_cpus(void)
+static void __init smp_boot_cpus(unsigned int max_cpus)
{
int apicid, cpu, bit;
@@ -1057,6 +1006,7 @@
* We have the boot CPU online for sure.
*/
set_bit(0, &cpu_online_map);
+ set_bit(0, &cpu_callout_map);
boot_cpu_logical_apicid = logical_smp_processor_id();
map_cpu_to_boot_apicid(0, boot_cpu_apicid);
@@ -1073,11 +1023,11 @@
#ifndef CONFIG_VISWS
io_apic_irqs = 0;
#endif
- cpu_online_map = phys_cpu_present_map = 1;
+ phys_cpu_present_map = 1;
if (APIC_init_uniprocessor())
printk(KERN_NOTICE "Local APIC not detected."
" Using dummy APIC emulation.\n");
- goto smp_done;
+ return;
}
/*
@@ -1102,8 +1052,8 @@
#ifndef CONFIG_VISWS
io_apic_irqs = 0;
#endif
- cpu_online_map = phys_cpu_present_map = 1;
- goto smp_done;
+ phys_cpu_present_map = 1;
+ return;
}
verify_local_APIC();
@@ -1117,8 +1067,8 @@
#ifndef CONFIG_VISWS
io_apic_irqs = 0;
#endif
- cpu_online_map = phys_cpu_present_map = 1;
- goto smp_done;
+ phys_cpu_present_map = 1;
+ return;
}
connect_bsp_APIC();
@@ -1190,7 +1140,7 @@
} else {
unsigned long bogosum = 0;
for (cpu = 0; cpu < NR_CPUS; cpu++)
- if (cpu_online_map & (1<<cpu))
+ if (cpu_callout_map & (1<<cpu))
bogosum += cpu_data[cpu].loops_per_jiffy;
printk(KERN_INFO "Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
cpucount+1,
@@ -1213,10 +1163,10 @@
for (cpu = 0; cpu < NR_CPUS; cpu++) {
int i;
- if (!cpu_online(cpu)) continue;
+ if (!test_bit(cpu, &cpu_callout_map)) continue;
for (i = 0; i < NR_CPUS; i++) {
- if (i == cpu || !cpu_online(i))
+ if (i == cpu || !test_bit(i, &cpu_callout_map))
continue;
if (phys_proc_id[cpu] == phys_proc_id[i]) {
cpu_sibling_map[cpu] = i;
@@ -1240,17 +1190,40 @@
setup_IO_APIC();
#endif
- /*
- * Set up all local APIC timers in the system:
- */
- setup_APIC_clocks();
+ setup_boot_APIC_clock();
/*
* Synchronize the TSC with the AP
*/
if (cpu_has_tsc && cpucount)
synchronize_tsc_bp();
+}
-smp_done:
+/* These are wrappers to interface to the new boot process. Someone
+ who understands all this stuff should rewrite it properly. --RR 15/Jul/02 */
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ smp_boot_cpus(max_cpus);
+}
+
+int __devinit __cpu_up(unsigned int cpu)
+{
+ /* This only works at boot for x86. See "rewrite" above. */
+ if (test_bit(cpu, &smp_commenced_mask))
+ return -ENOSYS;
+
+ /* In case one didn't come up */
+ if (!test_bit(cpu, &cpu_callin_map))
+ return -EIO;
+
+ /* Unleash the CPU! */
+ set_bit(cpu, &smp_commenced_mask);
+ while (!test_bit(cpu, &cpu_online_map))
+ mb();
+ return 0;
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
zap_low_mappings();
}
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/asm-i386/apic.h working-2.5.25-hotcpu/include/asm-i386/apic.h
--- linux-2.5.25/include/asm-i386/apic.h Mon Apr 15 11:47:44 2002
+++ working-2.5.25-hotcpu/include/asm-i386/apic.h Mon Jul 15 18:22:21 2002
@@ -76,7 +76,8 @@
extern void setup_local_APIC (void);
extern void init_apic_mappings (void);
extern void smp_local_timer_interrupt (struct pt_regs * regs);
-extern void setup_APIC_clocks (void);
+extern void setup_boot_APIC_clock (void);
+extern void setup_secondary_APIC_clock (void);
extern void setup_apic_nmi_watchdog (void);
extern inline void nmi_watchdog_tick (struct pt_regs * regs);
extern int APIC_init_uniprocessor (void);
diff -urN -I \$.*\$ --exclude TAGS -X /home/rusty/current-dontdiff --minimal linux-2.5.25/include/asm-i386/smp.h working-2.5.25-hotcpu/include/asm-i386/smp.h
--- linux-2.5.25/include/asm-i386/smp.h Thu Jun 20 01:28:51 2002
+++ working-2.5.25-hotcpu/include/asm-i386/smp.h Mon Jul 15 14:46:12 2002
@@ -79,19 +79,13 @@
extern volatile int logical_apicid_to_cpu[MAX_APICID];
/*
- * General functions that each host system must provide.
- */
-
-extern void smp_boot_cpus(void);
-extern void smp_store_cpu_info(int id); /* Store per CPU info (like the initial udelay numbers */
-
-/*
* This function is needed by all SMP systems. It must _always_ be valid
* from the initial startup. We map APIC_BASE very early in page_setup(),
* so this is correct in the x86 case.
*/
#define smp_processor_id() (current_thread_info()->cpu)
+#define cpu_possible(cpu) (phys_cpu_present_map & (1<<(cpu)))
#define cpu_online(cpu) (cpu_online_map & (1<<(cpu)))
extern inline unsigned int num_online_cpus(void)
@@ -117,6 +111,13 @@
{
/* we don't want to mark this access volatile - bad code generation */
return GET_APIC_LOGICAL_ID(*(unsigned long *)(APIC_BASE+APIC_LDR));
+}
+
+extern volatile unsigned long cpu_callout_map;
+/* We don't mark CPUs online until __cpu_up(), so we need another measure */
+static inline int num_booting_cpus(void)
+{
+ return hweight32(cpu_callout_map);
}
#endif /* !__ASSEMBLY__ */
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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