* [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 18:05 ` Cyril Chemparathy 0 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 18:05 UTC (permalink / raw) To: linux-arm-kernel This patch fixes the /dev/mem driver to use phys_addr_t for physical addresses. This is required on PAE systems, especially those that run entirely out of >4G physical memory space. Signed-off-by: Cyril Chemparathy <cyril@ti.com> --- arch/arm/include/asm/io.h | 2 +- arch/arm/mm/mmap.c | 2 +- arch/ia64/include/asm/io.h | 2 +- arch/ia64/kernel/efi.c | 2 +- arch/sh/include/asm/io.h | 2 +- arch/sh/mm/mmap.c | 2 +- drivers/char/mem.c | 10 +++++----- 7 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index 35c1ed8..f52a93d 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -374,7 +374,7 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr); #ifdef CONFIG_MMU #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -extern int valid_phys_addr_range(unsigned long addr, size_t size); +extern int valid_phys_addr_range(phys_addr_t addr, size_t size); extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); extern int devmem_is_allowed(unsigned long pfn); #endif diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index ce8cb19..89f2b7f 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -279,7 +279,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t size) +int valid_phys_addr_range(phys_addr_t addr, size_t size) { if (addr < PHYS_OFFSET) return 0; diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h index 2c26321..74a7cc3 100644 --- a/arch/ia64/include/asm/io.h +++ b/arch/ia64/include/asm/io.h @@ -90,7 +90,7 @@ phys_to_virt (unsigned long address) #define ARCH_HAS_VALID_PHYS_ADDR_RANGE extern u64 kern_mem_attribute (unsigned long phys_addr, unsigned long size); -extern int valid_phys_addr_range (unsigned long addr, size_t count); /* efi.c */ +extern int valid_phys_addr_range (phys_addr_t addr, size_t count); /* efi.c */ extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count); /* diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c index d37bbd4..f034563 100644 --- a/arch/ia64/kernel/efi.c +++ b/arch/ia64/kernel/efi.c @@ -870,7 +870,7 @@ kern_mem_attribute (unsigned long phys_addr, unsigned long size) EXPORT_SYMBOL(kern_mem_attribute); int -valid_phys_addr_range (unsigned long phys_addr, unsigned long size) +valid_phys_addr_range (phys_addr_t phys_addr, unsigned long size) { u64 attr; diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h index 0cf60a6..c4302a5 100644 --- a/arch/sh/include/asm/io.h +++ b/arch/sh/include/asm/io.h @@ -382,7 +382,7 @@ static inline int iounmap_fixed(void __iomem *addr) { return -EINVAL; } #define xlate_dev_kmem_ptr(p) p #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -int valid_phys_addr_range(unsigned long addr, size_t size); +int valid_phys_addr_range(phys_addr_t addr, size_t size); int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); #endif /* __KERNEL__ */ diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c index afeb710..80bf494 100644 --- a/arch/sh/mm/mmap.c +++ b/arch/sh/mm/mmap.c @@ -238,7 +238,7 @@ bottomup: * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t count) +int valid_phys_addr_range(phys_addr_t addr, size_t count) { if (addr < __MEMORY_START) return 0; diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 0537903..c6fa3bc 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -48,7 +48,7 @@ static inline unsigned long size_inside_page(unsigned long start, } #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE -static inline int valid_phys_addr_range(unsigned long addr, size_t count) +static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) { return addr + count <= __pa(high_memory); } @@ -96,7 +96,7 @@ void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr) static ssize_t read_mem(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t read, sz; char *ptr; @@ -153,7 +153,7 @@ static ssize_t read_mem(struct file *file, char __user *buf, static ssize_t write_mem(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t written, sz; unsigned long copied; void *ptr; @@ -226,7 +226,7 @@ int __weak phys_mem_access_prot_allowed(struct file *file, * */ #ifdef pgprot_noncached -static int uncached_access(struct file *file, unsigned long addr) +static int uncached_access(struct file *file, phys_addr_t addr) { #if defined(CONFIG_IA64) /* @@ -258,7 +258,7 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached - unsigned long offset = pfn << PAGE_SHIFT; + phys_addr_t offset = pfn << PAGE_SHIFT; if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 18:05 ` Cyril Chemparathy 0 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 18:05 UTC (permalink / raw) To: linux-arm-kernel, linux-ia64, linux-kernel, linux-sh Cc: arnd, cyril, dhowells, fenghua.yu, gregkh, lethal, linux, nico, rob.herring, tony.luck, tony, will.deacon This patch fixes the /dev/mem driver to use phys_addr_t for physical addresses. This is required on PAE systems, especially those that run entirely out of >4G physical memory space. Signed-off-by: Cyril Chemparathy <cyril@ti.com> --- arch/arm/include/asm/io.h | 2 +- arch/arm/mm/mmap.c | 2 +- arch/ia64/include/asm/io.h | 2 +- arch/ia64/kernel/efi.c | 2 +- arch/sh/include/asm/io.h | 2 +- arch/sh/mm/mmap.c | 2 +- drivers/char/mem.c | 10 +++++----- 7 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index 35c1ed8..f52a93d 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -374,7 +374,7 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr); #ifdef CONFIG_MMU #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -extern int valid_phys_addr_range(unsigned long addr, size_t size); +extern int valid_phys_addr_range(phys_addr_t addr, size_t size); extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); extern int devmem_is_allowed(unsigned long pfn); #endif diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index ce8cb19..89f2b7f 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -279,7 +279,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t size) +int valid_phys_addr_range(phys_addr_t addr, size_t size) { if (addr < PHYS_OFFSET) return 0; diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h index 2c26321..74a7cc3 100644 --- a/arch/ia64/include/asm/io.h +++ b/arch/ia64/include/asm/io.h @@ -90,7 +90,7 @@ phys_to_virt (unsigned long address) #define ARCH_HAS_VALID_PHYS_ADDR_RANGE extern u64 kern_mem_attribute (unsigned long phys_addr, unsigned long size); -extern int valid_phys_addr_range (unsigned long addr, size_t count); /* efi.c */ +extern int valid_phys_addr_range (phys_addr_t addr, size_t count); /* efi.c */ extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count); /* diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c index d37bbd4..f034563 100644 --- a/arch/ia64/kernel/efi.c +++ b/arch/ia64/kernel/efi.c @@ -870,7 +870,7 @@ kern_mem_attribute (unsigned long phys_addr, unsigned long size) EXPORT_SYMBOL(kern_mem_attribute); int -valid_phys_addr_range (unsigned long phys_addr, unsigned long size) +valid_phys_addr_range (phys_addr_t phys_addr, unsigned long size) { u64 attr; diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h index 0cf60a6..c4302a5 100644 --- a/arch/sh/include/asm/io.h +++ b/arch/sh/include/asm/io.h @@ -382,7 +382,7 @@ static inline int iounmap_fixed(void __iomem *addr) { return -EINVAL; } #define xlate_dev_kmem_ptr(p) p #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -int valid_phys_addr_range(unsigned long addr, size_t size); +int valid_phys_addr_range(phys_addr_t addr, size_t size); int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); #endif /* __KERNEL__ */ diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c index afeb710..80bf494 100644 --- a/arch/sh/mm/mmap.c +++ b/arch/sh/mm/mmap.c @@ -238,7 +238,7 @@ bottomup: * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t count) +int valid_phys_addr_range(phys_addr_t addr, size_t count) { if (addr < __MEMORY_START) return 0; diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 0537903..c6fa3bc 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -48,7 +48,7 @@ static inline unsigned long size_inside_page(unsigned long start, } #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE -static inline int valid_phys_addr_range(unsigned long addr, size_t count) +static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) { return addr + count <= __pa(high_memory); } @@ -96,7 +96,7 @@ void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr) static ssize_t read_mem(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t read, sz; char *ptr; @@ -153,7 +153,7 @@ static ssize_t read_mem(struct file *file, char __user *buf, static ssize_t write_mem(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t written, sz; unsigned long copied; void *ptr; @@ -226,7 +226,7 @@ int __weak phys_mem_access_prot_allowed(struct file *file, * */ #ifdef pgprot_noncached -static int uncached_access(struct file *file, unsigned long addr) +static int uncached_access(struct file *file, phys_addr_t addr) { #if defined(CONFIG_IA64) /* @@ -258,7 +258,7 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached - unsigned long offset = pfn << PAGE_SHIFT; + phys_addr_t offset = pfn << PAGE_SHIFT; if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 18:05 ` Cyril Chemparathy 0 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 18:05 UTC (permalink / raw) To: linux-arm-kernel This patch fixes the /dev/mem driver to use phys_addr_t for physical addresses. This is required on PAE systems, especially those that run entirely out of >4G physical memory space. Signed-off-by: Cyril Chemparathy <cyril@ti.com> --- arch/arm/include/asm/io.h | 2 +- arch/arm/mm/mmap.c | 2 +- arch/ia64/include/asm/io.h | 2 +- arch/ia64/kernel/efi.c | 2 +- arch/sh/include/asm/io.h | 2 +- arch/sh/mm/mmap.c | 2 +- drivers/char/mem.c | 10 +++++----- 7 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index 35c1ed8..f52a93d 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -374,7 +374,7 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr); #ifdef CONFIG_MMU #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -extern int valid_phys_addr_range(unsigned long addr, size_t size); +extern int valid_phys_addr_range(phys_addr_t addr, size_t size); extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); extern int devmem_is_allowed(unsigned long pfn); #endif diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index ce8cb19..89f2b7f 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -279,7 +279,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm) * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t size) +int valid_phys_addr_range(phys_addr_t addr, size_t size) { if (addr < PHYS_OFFSET) return 0; diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h index 2c26321..74a7cc3 100644 --- a/arch/ia64/include/asm/io.h +++ b/arch/ia64/include/asm/io.h @@ -90,7 +90,7 @@ phys_to_virt (unsigned long address) #define ARCH_HAS_VALID_PHYS_ADDR_RANGE extern u64 kern_mem_attribute (unsigned long phys_addr, unsigned long size); -extern int valid_phys_addr_range (unsigned long addr, size_t count); /* efi.c */ +extern int valid_phys_addr_range (phys_addr_t addr, size_t count); /* efi.c */ extern int valid_mmap_phys_addr_range (unsigned long pfn, size_t count); /* diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c index d37bbd4..f034563 100644 --- a/arch/ia64/kernel/efi.c +++ b/arch/ia64/kernel/efi.c @@ -870,7 +870,7 @@ kern_mem_attribute (unsigned long phys_addr, unsigned long size) EXPORT_SYMBOL(kern_mem_attribute); int -valid_phys_addr_range (unsigned long phys_addr, unsigned long size) +valid_phys_addr_range (phys_addr_t phys_addr, unsigned long size) { u64 attr; diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h index 0cf60a6..c4302a5 100644 --- a/arch/sh/include/asm/io.h +++ b/arch/sh/include/asm/io.h @@ -382,7 +382,7 @@ static inline int iounmap_fixed(void __iomem *addr) { return -EINVAL; } #define xlate_dev_kmem_ptr(p) p #define ARCH_HAS_VALID_PHYS_ADDR_RANGE -int valid_phys_addr_range(unsigned long addr, size_t size); +int valid_phys_addr_range(phys_addr_t addr, size_t size); int valid_mmap_phys_addr_range(unsigned long pfn, size_t size); #endif /* __KERNEL__ */ diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c index afeb710..80bf494 100644 --- a/arch/sh/mm/mmap.c +++ b/arch/sh/mm/mmap.c @@ -238,7 +238,7 @@ bottomup: * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. */ -int valid_phys_addr_range(unsigned long addr, size_t count) +int valid_phys_addr_range(phys_addr_t addr, size_t count) { if (addr < __MEMORY_START) return 0; diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 0537903..c6fa3bc 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -48,7 +48,7 @@ static inline unsigned long size_inside_page(unsigned long start, } #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE -static inline int valid_phys_addr_range(unsigned long addr, size_t count) +static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) { return addr + count <= __pa(high_memory); } @@ -96,7 +96,7 @@ void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr) static ssize_t read_mem(struct file *file, char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t read, sz; char *ptr; @@ -153,7 +153,7 @@ static ssize_t read_mem(struct file *file, char __user *buf, static ssize_t write_mem(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - unsigned long p = *ppos; + phys_addr_t p = *ppos; ssize_t written, sz; unsigned long copied; void *ptr; @@ -226,7 +226,7 @@ int __weak phys_mem_access_prot_allowed(struct file *file, * */ #ifdef pgprot_noncached -static int uncached_access(struct file *file, unsigned long addr) +static int uncached_access(struct file *file, phys_addr_t addr) { #if defined(CONFIG_IA64) /* @@ -258,7 +258,7 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached - unsigned long offset = pfn << PAGE_SHIFT; + phys_addr_t offset = pfn << PAGE_SHIFT; if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v2] /dev/mem: use phys_addr_t for physical addresses 2012-09-12 18:05 ` Cyril Chemparathy (?) @ 2012-09-12 18:15 ` Greg KH -1 siblings, 0 replies; 9+ messages in thread From: Greg KH @ 2012-09-12 18:15 UTC (permalink / raw) To: linux-arm-kernel On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: > This patch fixes the /dev/mem driver to use phys_addr_t for physical > addresses. This is required on PAE systems, especially those that run > entirely out of >4G physical memory space. What is the symptom if this patch is not applied? Does it need to be backported to older kernels? If so, which ones? thanks, greg k-h ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 18:15 ` Greg KH 0 siblings, 0 replies; 9+ messages in thread From: Greg KH @ 2012-09-12 18:15 UTC (permalink / raw) To: Cyril Chemparathy Cc: linux-arm-kernel, linux-ia64, linux-kernel, linux-sh, arnd, dhowells, fenghua.yu, lethal, linux, nico, rob.herring, tony.luck, tony, will.deacon On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: > This patch fixes the /dev/mem driver to use phys_addr_t for physical > addresses. This is required on PAE systems, especially those that run > entirely out of >4G physical memory space. What is the symptom if this patch is not applied? Does it need to be backported to older kernels? If so, which ones? thanks, greg k-h ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 18:15 ` Greg KH 0 siblings, 0 replies; 9+ messages in thread From: Greg KH @ 2012-09-12 18:15 UTC (permalink / raw) To: linux-arm-kernel On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: > This patch fixes the /dev/mem driver to use phys_addr_t for physical > addresses. This is required on PAE systems, especially those that run > entirely out of >4G physical memory space. What is the symptom if this patch is not applied? Does it need to be backported to older kernels? If so, which ones? thanks, greg k-h ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2] /dev/mem: use phys_addr_t for physical addresses 2012-09-12 18:15 ` Greg KH (?) @ 2012-09-12 22:54 ` Cyril Chemparathy -1 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 22:54 UTC (permalink / raw) To: linux-arm-kernel Greg, On 9/12/2012 2:15 PM, Greg KH wrote: > On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: >> This patch fixes the /dev/mem driver to use phys_addr_t for physical >> addresses. This is required on PAE systems, especially those that run >> entirely out of >4G physical memory space. > > What is the symptom if this patch is not applied? Does it need to be > backported to older kernels? If so, which ones? > As far as I can tell, this change only benefits platforms where lowmem lies outside the 32-bit addressable range. On the ARM based KeyStone platform, all of our memory is located above the 4GB limit at 0x8:0000:0000. On this platform, trying to read lowmem breaks as follows: # dd if=/dev/mem of=/dev/null bs=4k count=1 skipƒ88608 dd: /dev/mem: Bad address Assuming that we are unique in this regard (i.e. lowmem outside 4GB), I don't see any reason to backport this to earlier kernels. -- Thanks - Cyril ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 22:54 ` Cyril Chemparathy 0 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 22:54 UTC (permalink / raw) To: Greg KH Cc: linux-arm-kernel, linux-ia64, linux-kernel, linux-sh, arnd, dhowells, fenghua.yu, lethal, linux, nico, rob.herring, tony.luck, tony, will.deacon Greg, On 9/12/2012 2:15 PM, Greg KH wrote: > On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: >> This patch fixes the /dev/mem driver to use phys_addr_t for physical >> addresses. This is required on PAE systems, especially those that run >> entirely out of >4G physical memory space. > > What is the symptom if this patch is not applied? Does it need to be > backported to older kernels? If so, which ones? > As far as I can tell, this change only benefits platforms where lowmem lies outside the 32-bit addressable range. On the ARM based KeyStone platform, all of our memory is located above the 4GB limit at 0x8:0000:0000. On this platform, trying to read lowmem breaks as follows: # dd if==/dev/mem of=/dev/null bs==4k count=1 skip=8388608 dd: /dev/mem: Bad address Assuming that we are unique in this regard (i.e. lowmem outside 4GB), I don't see any reason to backport this to earlier kernels. -- Thanks - Cyril ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2] /dev/mem: use phys_addr_t for physical addresses @ 2012-09-12 22:54 ` Cyril Chemparathy 0 siblings, 0 replies; 9+ messages in thread From: Cyril Chemparathy @ 2012-09-12 22:54 UTC (permalink / raw) To: linux-arm-kernel Greg, On 9/12/2012 2:15 PM, Greg KH wrote: > On Wed, Sep 12, 2012 at 02:05:58PM -0400, Cyril Chemparathy wrote: >> This patch fixes the /dev/mem driver to use phys_addr_t for physical >> addresses. This is required on PAE systems, especially those that run >> entirely out of >4G physical memory space. > > What is the symptom if this patch is not applied? Does it need to be > backported to older kernels? If so, which ones? > As far as I can tell, this change only benefits platforms where lowmem lies outside the 32-bit addressable range. On the ARM based KeyStone platform, all of our memory is located above the 4GB limit at 0x8:0000:0000. On this platform, trying to read lowmem breaks as follows: # dd if==/dev/mem of=/dev/null bs==4k count=1 skip=8388608 dd: /dev/mem: Bad address Assuming that we are unique in this regard (i.e. lowmem outside 4GB), I don't see any reason to backport this to earlier kernels. -- Thanks - Cyril ^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2012-09-12 22:54 UTC | newest] Thread overview: 9+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-09-12 18:05 [PATCH v2] /dev/mem: use phys_addr_t for physical addresses Cyril Chemparathy 2012-09-12 18:05 ` Cyril Chemparathy 2012-09-12 18:05 ` Cyril Chemparathy 2012-09-12 18:15 ` Greg KH 2012-09-12 18:15 ` Greg KH 2012-09-12 18:15 ` Greg KH 2012-09-12 22:54 ` Cyril Chemparathy 2012-09-12 22:54 ` Cyril Chemparathy 2012-09-12 22:54 ` Cyril Chemparathy
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