On Fri, 2015-07-24 at 17:26 +0100, Will Deacon wrote:
On Fri, Jul 24, 2015 at 05:21:49PM +0100, Catalin Marinas wrote:
On Fri, Jul 24, 2015 at 03:57:08PM +0100, Will Deacon wrote:
On Tue, Jul 21, 2015 at 10:59:19PM +0100, Jonathan (Zhixiong) Zhang wrote:
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr) +{
- pgprot_t prot;
- prot = efi_mem_attributes(addr);
- if (prot & EFI_MEMORY_UC)
return PROT_DEVICE_nGnRnE;- if (prot & EFI_MEMORY_WC)
return PROT_NORMAL_NC;Can we not use pgprot_noncached and pgprot_writecombine for these two?
Actually, why do we even use pgprot_t for prot here? EFI_MEMORY_* don't have anything to do with the arch-specific pgprot_t.
Good point; the pgprot_t confused me, so my suggestion is much use after ll. We're better off with a u64 to avoid further confusion.
Isn't the whole point of arch_apei_get_mem_attribute() to turn an arch-independent memory attribute (EFI_MEMORY_*) into an arch-specific value to pass to ioremap_page_range()?
I don't see how you can do that any other way than by using pgprot_t.
Really, the problem here is that ioremap_page_caller() has no notion of "map this range in a firmware-compatible manner". If we could do, for example,
ioremap_page_range(vaddr, vend, paddr, PAGE_FW_COMPAT);
that would allow the innards of the arch-ioremap to figure out exactly how to map this range so that the firmware could access it coherently.
I suggested this previously but it didn't gain any traction.