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Message-ID: <20140319204230.GA13767@home.buserror.net>
Date: Wed, 19 Mar 2014 15:42:31 -0500
From: Scott Wood <scottwood@...escale.com>
To: LEROY Christophe <christophe.leroy@....fr>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC, v3] powerpc: Loading kernels over 8Mbytes without
CONFIG_PIN_TLB
On Sun, Dec 15, 2013 at 04:09:57PM +0100, LEROY Christophe wrote:
> Hereunder is a try to implement the sizing of the initial memory size based on
> initial-mapped-area size given by uboot in r7.
> As this has an impact on all powerpc platforms due to the need to provide the
> info up to function setup_initial_memory_limit(), I'm not completly sure of the
> proper implementation.
> Thanks to provide comments.
>
> Today on the 8xx, the only way to load kernels whose size is greater than
> 8Mbytes is to activate CONFIG_PIN_TLB. Otherwise, the physical memory initially
> mapped is limited to 8Mbytes. This patch uses the size of initial memory mapped
> by the bootloader and given to the kernel through register r7.
> This is done regardless of whether CONFIG_PIN_TLB is active or not. It allows to
> load "big" kernels (for instance when activating CONFIG_LOCKDEP_SUPPORT) without
> having to activate CONFIG_PIN_TLB.
>
> Not-yet-signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>
> ---
> Ce courrier électronique ne contient aucun virus ou logiciel malveillant parce que la protection avast! Antivirus est active.
> http://www.avast.com
>
> Index: linux/arch/powerpc/include/asm/mmu.h
> ===================================================================
> --- linux/arch/powerpc/include/asm/mmu.h (revision 5484)
> +++ linux/arch/powerpc/include/asm/mmu.h (copie de travail)
> @@ -138,7 +138,8 @@
> extern void early_init_mmu_secondary(void);
>
> extern void setup_initial_memory_limit(phys_addr_t first_memblock_base,
> - phys_addr_t first_memblock_size);
> + phys_addr_t first_memblock_size,
> + u64 init_mem_size);
What is the difference between first_memblock_size and init_mem_size, in
terms of what you expect setup_initial_memory_limit to do with them?
Can you just pass in min(first_memblock_size, init_mem_size), with the
non-ePAPR fallback handled in head_8xx.S (just load r30 with 8M instead
of zero)?
> #ifdef CONFIG_PPC64
> /* This is our real memory area size on ppc64 server, on embedded, we
> Index: linux/arch/powerpc/kernel/head_8xx.S
> ===================================================================
> --- linux/arch/powerpc/kernel/head_8xx.S (revision 5484)
> +++ linux/arch/powerpc/kernel/head_8xx.S (copie de travail)
> @@ -31,6 +31,8 @@
> #include <asm/asm-offsets.h>
> #include <asm/ptrace.h>
>
> +#define EPAPR_MAGIC 0x65504150
> +
> /* Macro to make the code more readable. */
> #ifdef CONFIG_8xx_CPU6
> #define DO_8xx_CPU6(val, reg) \
> @@ -77,10 +79,19 @@
> .globl __start
> __start:
> mr r31,r3 /* save device tree ptr */
> + li r30,0
>
> + lis r8,EPAPR_MAGIC@h
> + ori r8,r8, EPAPR_MAGIC@l
> + cmpw cr0,r8, r6
Whitespace
> + bne 1f
> +
> + mr r30,r7 /* save initial ram size */
> +
> /* We have to turn on the MMU right away so we get cache modes
> * set correctly.
> */
> +1:
> bl initial_mmu
>
> /* We now have the lower 8 Meg mapped into TLB entries, and the caches
> @@ -717,6 +728,8 @@
> */
> li r3,0
> mr r4,r31
> + li r5,0
> + mr r6,r30
> bl machine_init
> bl MMU_init
>
> @@ -841,11 +854,17 @@
> ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
> mtspr SPRN_MD_RPN, r8
>
> + /* Map two more 8M kernel data pages if needed
> + * We check how much memory is mapped by the bootloader
> + */
Whitespace
> Index: linux/arch/powerpc/kernel/prom.c
> ===================================================================
> --- linux/arch/powerpc/kernel/prom.c (revision 5484)
> +++ linux/arch/powerpc/kernel/prom.c (copie de travail)
> @@ -649,7 +649,7 @@
> }
> }
>
> -void __init early_init_devtree(void *params)
> +void __init early_init_devtree(void *params, u64 init_mem_size)
> {
> phys_addr_t limit;
>
> @@ -697,7 +697,7 @@
> /* make sure we've parsed cmdline for mem= before this */
> if (memory_limit)
> first_memblock_size = min_t(u64, first_memblock_size, memory_limit);
> - setup_initial_memory_limit(memstart_addr, first_memblock_size);
> + setup_initial_memory_limit(memstart_addr, first_memblock_size, init_mem_size);
Line length.
Yes, I know there's an existing violation on the previous line. :-)
> Index: linux/arch/powerpc/mm/init_32.c
> ===================================================================
> --- linux/arch/powerpc/mm/init_32.c (revision 5484)
> +++ linux/arch/powerpc/mm/init_32.c (copie de travail)
> @@ -206,19 +206,16 @@
>
> #ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
> void setup_initial_memory_limit(phys_addr_t first_memblock_base,
> - phys_addr_t first_memblock_size)
> + phys_addr_t first_memblock_size,
> + u64 init_mem_size)
> {
> /* We don't currently support the first MEMBLOCK not mapping 0
> * physical on those processors
> */
> BUG_ON(first_memblock_base != 0);
>
> -#ifdef CONFIG_PIN_TLB
> - /* 8xx can only access 24MB at the moment */
> - memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01800000));
> -#else
> - /* 8xx can only access 8MB at the moment */
> - memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
> -#endif
> + if (!init_mem_size)
> + init_mem_size = 0x00800000;
> + memblock_set_current_limit(min_t(u64, first_memblock_size, init_mem_size));
Line length
> }
> #endif /* CONFIG_8xx */
> Index: linux/arch/powerpc/mm/ppc_mmu_32.c
> ===================================================================
> --- linux/arch/powerpc/mm/ppc_mmu_32.c (revision 5484)
> +++ linux/arch/powerpc/mm/ppc_mmu_32.c (copie de travail)
> @@ -273,7 +273,8 @@
> }
>
> void setup_initial_memory_limit(phys_addr_t first_memblock_base,
> - phys_addr_t first_memblock_size)
> + phys_addr_t first_memblock_size,
> + u64 init_mem_size)
> {
> /* We don't currently support the first MEMBLOCK not mapping 0
> * physical on those processors
> Index: linux/arch/powerpc/mm/tlb_nohash.c
> ===================================================================
> --- linux/arch/powerpc/mm/tlb_nohash.c (revision 5484)
> +++ linux/arch/powerpc/mm/tlb_nohash.c (copie de travail)
> @@ -654,7 +654,8 @@
> }
>
> void setup_initial_memory_limit(phys_addr_t first_memblock_base,
> - phys_addr_t first_memblock_size)
> + phys_addr_t first_memblock_size,
> + u64 init_mem_size)
> {
> /* On non-FSL Embedded 64-bit, we adjust the RMA size to match
> * the bolted TLB entry. We know for now that only 1G
It seems a bit odd for this function to take init_mem_size on these other
platforms, but not use it.
-Scott
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