| Message ID | 1362526811-15768-1-git-send-email-scott.jiang.linux@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello, On 3/6/2013 12:40 AM, Scott Jiang wrote: > No MMU systems also make use of this function to do mmap. > > Signed-off-by: Scott Jiang <scott.jiang.linux@gmail.com> > --- > drivers/base/dma-mapping.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c > index 0ce39a3..ae655b2 100644 > --- a/drivers/base/dma-mapping.c > +++ b/drivers/base/dma-mapping.c > @@ -245,7 +245,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, > void *cpu_addr, dma_addr_t dma_addr, size_t size) > { > int ret = -ENXIO; > -#ifdef CONFIG_MMU > unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; > unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; > unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); > @@ -262,7 +261,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, > user_count << PAGE_SHIFT, > vma->vm_page_prot); > } > -#endif /* CONFIG_MMU */ > > return ret; > } I really have no experience with NO-MMU kernels, could you explain a bit more how this is useful for handling mmap on such systems? How remap_pfn_range() is handled on no-mmu systems? I've thought that mmap on no-mmu systems is silently replaced by a call to get_unmapped_area(), but it looks that there is still a call to mmap function. Best regards
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c index 0ce39a3..ae655b2 100644 --- a/drivers/base/dma-mapping.c +++ b/drivers/base/dma-mapping.c @@ -245,7 +245,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t dma_addr, size_t size) { int ret = -ENXIO; -#ifdef CONFIG_MMU unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT; unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr)); @@ -262,7 +261,6 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, user_count << PAGE_SHIFT, vma->vm_page_prot); } -#endif /* CONFIG_MMU */ return ret; }
No MMU systems also make use of this function to do mmap. Signed-off-by: Scott Jiang <scott.jiang.linux@gmail.com> --- drivers/base/dma-mapping.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-)