On Tue, Apr 9, 2013 at 8:08 PM, Rob Herring <[email protected]> wrote: > From: Rob Herring <[email protected]> > > Atomic operations are undefined behavior on ARM for device or strongly > ordered memory types. So use write-combine variants for mappings. This > corresponds to normal, non-cacheable memory on ARM. For many other > architectures, this change should not change the mapping type.
This is going to make ramconsole less reliable. A debugging printk followed by a __raw_writel that causes an immediate hard crash is likely to lose the last updates, including the most useful message, in the write buffers. Also, isn't this patch unnecessary after patch 3 in this set? > Signed-off-by: Rob Herring <[email protected]> > Cc: Anton Vorontsov <[email protected]> > Cc: Colin Cross <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: Tony Luck <[email protected]> > Cc: [email protected] > --- > fs/pstore/ram_core.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c > index 0306303..e126d9f 100644 > --- a/fs/pstore/ram_core.c > +++ b/fs/pstore/ram_core.c > @@ -337,7 +337,7 @@ static void *persistent_ram_vmap(phys_addr_t start, > size_t size) > page_start = start - offset_in_page(start); > page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE); > > - prot = pgprot_noncached(PAGE_KERNEL); > + prot = pgprot_writecombine(PAGE_KERNEL); Is this necessary? Won't pgprot_noncached already be normal memory? > pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL); > if (!pages) { > @@ -364,7 +364,7 @@ static void *persistent_ram_iomap(phys_addr_t start, > size_t size) > return NULL; > } > > - return ioremap(start, size); > + return ioremap_wc(start, size); ioremap_wc corresponds to MT_DEVICE_WC, which is still device memory, so I don't see how this helps solve the problem in the commit message. > } > > static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
