[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v5 1/7] efi: Use early_mem*() instead of early_io*()
On 18/06/14 13:17, Matt Fleming wrote: > (Pulling in Mark Salter for early_ioremap() knowledge) > > On Fri, 13 Jun, at 07:00:17PM, Daniel Kiper wrote: >> Use early_mem*() instead of early_io*() because all mapped EFI regions >> are true RAM not I/O regions. Additionally, I/O family calls do not work >> correctly under Xen in our case. AIUI, early_io*() maps/unmaps real machine >> addresses. However, all artificial EFI structures created under Xen live >> in dom0 memory and should be mapped/unmapped using early_mem*() family >> calls which map domain memory. >> >> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx> >> --- >> arch/x86/platform/efi/efi.c | 42 >> +++++++++++++++++++++--------------------- >> drivers/firmware/efi/efi.c | 4 ++-- >> 2 files changed, 23 insertions(+), 23 deletions(-) >> >> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c >> index 87fc96b..dd1e351 100644 >> --- a/arch/x86/platform/efi/efi.c >> +++ b/arch/x86/platform/efi/efi.c >> @@ -427,7 +427,7 @@ void __init efi_unmap_memmap(void) >> { >> clear_bit(EFI_MEMMAP, &efi.flags); >> if (memmap.map) { >> - early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size); >> + early_memunmap(memmap.map, memmap.nr_map * memmap.desc_size); >> memmap.map = NULL; >> } >> } >> @@ -467,12 +467,12 @@ static int __init efi_systab_init(void *phys) >> if (!data) >> return -ENOMEM; >> } >> - systab64 = early_ioremap((unsigned long)phys, >> - sizeof(*systab64)); >> + systab64 = early_memremap((unsigned long)phys, >> + sizeof(*systab64)); > > Please don't misalign the arguments :-( This makes the diff harder to > read when all you're doing is changing the function call. You're > indentation isn't an improvement. > > As Matthew pointed out we may also need to access EFI mapped flash > devices. > > Now, the only difference between early_memremap() and early_ioremap(), > at least on x86, is PAGE_KERNEL vs. PAGE_KERNEL_IO, where PAGE_KERNEL_IO > has the additional _PAGE_BIT_IOMAP bit set in the pte. But that's a > software bit for x86. _PAGE_BIT_IOMAP is supposed to be going away... > So, even though this change should be harmless, it's not clear to me why > this change is needed. You say "I/O family calls do not work correctly > under Xen in our case", but could you provide some more explanation as > to why they don't work correctly? _PAGE_BIT_IOMAP causes a Xen PV guest to skip the PFN to MFN conversion when building the PTE. Using it for RAM will attempt to map the wrong machine frame. David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |