arch/sparc: support NR_CPUS = 4096 (c79a1373) · Commits · 戴 / test

Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info() only allocates a single page for NR_CPUS mondo entries. Thus we cannot use all 4096 CPUs on some SPARC platforms. To fix, allocate (2^order) pages where order is set according to the size of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa are not used in asm code, there are no imm13 offsets from the base PA that will break because they can only reach one page. Orabug: 25505750 Signed-off-by:

Jane Chu <jane.chu@oracle.com> Reviewed-by:

Bob Picco <bob.picco@oracle.com> Reviewed-by:

Atish Patra <atish.patra@oracle.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

arch/sparc/Kconfig

+2 −2

Original line number	Diff line number	Diff line
		@@ -192,9 +192,9 @@ config NR_CPUS
		int "Maximum number of CPUs"
		depends on SMP
		range 2 32 if SPARC32
		range 2 1024 if SPARC64
		range 2 4096 if SPARC64
		default 32 if SPARC32
		default 64 if SPARC64
		default 4096 if SPARC64

		source kernel/Kconfig.hz

arch/sparc/kernel/irq_64.c

+13 −4

Original line number	Diff line number	Diff line
		@@ -1034,17 +1034,26 @@ static void __init init_cpu_send_mondo_info(struct trap_per_cpu *tb)
		{
		#ifdef CONFIG_SMP
		unsigned long page;
		void mondo, p;

		BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
		BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);

		/* Make sure mondo block is 64byte aligned */
		p = kzalloc(127, GFP_KERNEL);
		if (!p) {
		prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
		prom_halt();
		}
		mondo = (void *)(((unsigned long)p + 63) & ~0x3f);
		tb->cpu_mondo_block_pa = __pa(mondo);

		page = get_zeroed_page(GFP_KERNEL);
		if (!page) {
		prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
		prom_printf("SUN4V: Error, cannot allocate cpu list page.\n");
		prom_halt();
		}

		tb->cpu_mondo_block_pa = __pa(page);
		tb->cpu_list_pa = __pa(page + 64);
		tb->cpu_list_pa = __pa(page);
		#endif
		}

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