Re: [PATCH 2/3] MIPS: OCTEON: support disabling HOTPLUG_CPU run-time

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On 06/16/2014 01:06 PM, Aaro Koskinen wrote:
If nosmp kernel option given, we can assume HOTPLUG_CPU is disabled.
This is needed in order to be able to run the same kernel binary on
single core OCTEONs with older/incompatible bootloaders.

Signed-off-by: Aaro Koskinen <aaro.koskinen@xxxxxx>
Cc: linux-watchdog@xxxxxxxxxxxxxxx
---
  arch/mips/cavium-octeon/smp.c      |  5 ++-
  drivers/watchdog/octeon-wdt-main.c | 62 +++++++++++++++++++++-----------------
  2 files changed, 38 insertions(+), 29 deletions(-)


The changes to these two files are almost unrelated, they really need to be in separate patches.



diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index 2c8d156..ea96930 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -84,6 +84,9 @@ static void octeon_smp_hotplug_setup(void)
  #ifdef CONFIG_HOTPLUG_CPU
  	struct linux_app_boot_info *labi;

+	if (!setup_max_cpus)
+		return;
+
  	labi = (struct linux_app_boot_info *)PHYS_TO_XKSEG_CACHED(LABI_ADDR_IN_BOOTLOADER);
  	if (labi->labi_signature != LABI_SIGNATURE)
  		panic("The bootloader version on this board is incorrect.");
@@ -129,7 +132,7 @@ static void octeon_smp_setup(void)
  	 * will assign CPU numbers for possible cores as well.	Cores
  	 * are always consecutively numberd from 0.
  	 */
-	for (id = 0; id < num_cores && id < NR_CPUS; id++) {
+	for (id = 0; setup_max_cpus && id < num_cores && id < NR_CPUS; id++) {
  		if (!(core_mask & (1 << id))) {
  			set_cpu_possible(cpus, true);
  			__cpu_number_map[id] = cpus;


This arch/mips/cavium-octeon/smp.c part seems plausible, so for it only you can add ...

Acked-by: David Daney <david.daney@xxxxxxxxxx>


diff --git a/drivers/watchdog/octeon-wdt-main.c b/drivers/watchdog/octeon-wdt-main.c
index 4baf2d7..c5aee12 100644
--- a/drivers/watchdog/octeon-wdt-main.c
+++ b/drivers/watchdog/octeon-wdt-main.c
@@ -145,35 +145,39 @@ static void __init octeon_wdt_build_stage1(void)

  	uasm_i_mfc0(&p, K0, C0_STATUS);
  #ifdef CONFIG_HOTPLUG_CPU
-	uasm_il_bbit0(&p, &r, K0, ilog2(ST0_NMI), label_enter_bootloader);
+	if (setup_max_cpus)


This bit has nothing to do with setup_max_cpus, but rather if hot-plugging CPUs is possible.

There should be a separate variable to indicate if hot-plugging CPUs is possible which would be used here instead.

See my comments in patch 3/3 also.

+		uasm_il_bbit0(&p, &r, K0, ilog2(ST0_NMI),
+			      label_enter_bootloader);
  #endif
  	/* Force 64-bit addressing enabled */
  	uasm_i_ori(&p, K0, K0, ST0_UX | ST0_SX | ST0_KX);
  	uasm_i_mtc0(&p, K0, C0_STATUS);

  #ifdef CONFIG_HOTPLUG_CPU
-	uasm_i_mfc0(&p, K0, C0_EBASE);
-	/* Coreid number in K0 */
-	uasm_i_andi(&p, K0, K0, 0xf);
-	/* 8 * coreid in bits 16-31 */
-	uasm_i_dsll_safe(&p, K0, K0, 3 + 16);
-	uasm_i_ori(&p, K0, K0, 0x8001);
-	uasm_i_dsll_safe(&p, K0, K0, 16);
-	uasm_i_ori(&p, K0, K0, 0x0700);
-	uasm_i_drotr_safe(&p, K0, K0, 32);
-	/*
-	 * Should result in: 0x8001,0700,0000,8*coreid which is
-	 * CVMX_CIU_WDOGX(coreid) - 0x0500
-	 *
-	 * Now ld K0, CVMX_CIU_WDOGX(coreid)
-	 */
-	uasm_i_ld(&p, K0, 0x500, K0);
-	/*
-	 * If bit one set handle the NMI as a watchdog event.
-	 * otherwise transfer control to bootloader.
-	 */
-	uasm_il_bbit0(&p, &r, K0, 1, label_enter_bootloader);
-	uasm_i_nop(&p);
+	if (setup_max_cpus) {
+		uasm_i_mfc0(&p, K0, C0_EBASE);
+		/* Coreid number in K0 */
+		uasm_i_andi(&p, K0, K0, 0xf);
+		/* 8 * coreid in bits 16-31 */
+		uasm_i_dsll_safe(&p, K0, K0, 3 + 16);
+		uasm_i_ori(&p, K0, K0, 0x8001);
+		uasm_i_dsll_safe(&p, K0, K0, 16);
+		uasm_i_ori(&p, K0, K0, 0x0700);
+		uasm_i_drotr_safe(&p, K0, K0, 32);
+		/*
+		 * Should result in: 0x8001,0700,0000,8*coreid which is
+		 * CVMX_CIU_WDOGX(coreid) - 0x0500
+		 *
+		 * Now ld K0, CVMX_CIU_WDOGX(coreid)
+		 */
+		uasm_i_ld(&p, K0, 0x500, K0);
+		/*
+		 * If bit one set handle the NMI as a watchdog event.
+		 * otherwise transfer control to bootloader.
+		 */
+		uasm_il_bbit0(&p, &r, K0, 1, label_enter_bootloader);
+		uasm_i_nop(&p);
+	}
  #endif

  	/* Clear Dcache so cvmseg works right. */
@@ -194,11 +198,13 @@ static void __init octeon_wdt_build_stage1(void)
  	uasm_i_dmfc0(&p, K0, C0_DESAVE);

  #ifdef CONFIG_HOTPLUG_CPU
-	uasm_build_label(&l, p, label_enter_bootloader);
-	/* Jump to the bootloader and restore K0 */
-	UASM_i_LA(&p, K0, (long)octeon_bootloader_entry_addr);
-	uasm_i_jr(&p, K0);
-	uasm_i_dmfc0(&p, K0, C0_DESAVE);
+	if (setup_max_cpus) {
+		uasm_build_label(&l, p, label_enter_bootloader);
+		/* Jump to the bootloader and restore K0 */
+		UASM_i_LA(&p, K0, (long)octeon_bootloader_entry_addr);
+		uasm_i_jr(&p, K0);
+		uasm_i_dmfc0(&p, K0, C0_DESAVE);
+	}
  #endif
  	uasm_resolve_relocs(relocs, labels);





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