Re: [PATCH 1/4] Documentation: arm: [U]EFI runtime services

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 06/26/2013 07:38 AM, James Bottomley wrote:
> On Wed, 2013-06-26 at 14:59 +0100, Matt Fleming wrote:
>> On Wed, 26 Jun, at 03:53:11PM, Leif Lindholm wrote:
>>> It's completely feasible, but we'd need to use a different method to do
>>> the boot services call with a 1:1 mapping (idmap support is not available
>>> until much later in the boot process).
>>
>> At least if you no longer relied upon the idmap we could potentially
>> have a single efi_enter_virtual_mode() call-site in init/main.c, which
>> would be nice.
> 
> The fixed virtual address scheme currently being looked at for x86_64 to
> make SetVirtualAddressMap() kexec invariant doesn't work on 32 bit
> because the address space isn't big enough.  For ARM, given that we've
> much more opportunity to work with the vendors, can we just avoid
> transitioning to a virtual address map and always just install a
> physical mapping before doing efi calls?
> 

What we could do on x86-32 is to map from 0xc0000000 downwards.  It
wouldn't be invariant across kernel builds with different user/kernel
split... but I'm not sure we can win that one.

The other option is to say sod it and just use straight 1:1 mapping on
32 bits...

	-hpa


--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]

  Powered by Linux