[U-Boot] [PATCH 0/2] efi_loader: Add bounce buffers

[York Sun]

On 05/11/2016 10:04 AM, Alexander Graf wrote:
> 
> 
>> Am 11.05.2016 um 18:33 schrieb York Sun <york.sun at nxp.com>:
>>
>>> On 05/11/2016 09:25 AM, Alexander Graf wrote:
>>> While testing our shiny new EFI support, I stumbled across systems that
>>> have disk I/O hardware that can only access the lower 32bits of our
>>> physical address space.
>>>
>>> This is not a problem when running with the normal U-Boot flow, since we
>>> define all "pointers" that get in use in our environment, so we can just
>>> put them inside the lower 32bits.
>>>
>>> But when a higher level application such as an EFI payload comes across,
>>> it doesn't know about these constraints. So we need to allocate bounce
>>> buffers for the payload and use them instead.
>>
>> Alexander,
>>
>> The low 32-bit physical memory is required for this to work, isn't it? There was
>> a discussion to move to high memory for LS2080 so the memory can be continuous
>> for OS.
> 
> So how would that work in the non-efi case? Do you configure the smmu statically to give you an offset between device memory view and physical?

Alex,

We are still waiting for more thorough testing on all drivers. This was an
effort to provide continuous memory for OS. As you know, only 2GB memory is
available under 32-bit space. All other memory shows up at above 39-bit space.
Limited tests proved Linux can boot with the high memory. However, some drivers
may not be happy with the missing 32-bit memory space. The final call is not
made yet.

York

> 
> In that case we can probably extend the patch to make the config variable a max addr instead of bool. Then the bounce buffer would be inside the shifted 32bit window.
> 
> 
> Alex
> 
>>
>> York
>>
>>>
>>> Alexander Graf (2):
>>>  efi_loader: Add bounce buffer support
>>>  efi_loader: Select bounce buffers for known-bad boards
>>>
>>> configs/ls2080a_emu_defconfig                    |  1 +
>>> configs/ls2080a_simu_defconfig                   |  1 +
>>> configs/ls2080aqds_SECURE_BOOT_defconfig         |  1 +
>>> configs/ls2080aqds_defconfig                     |  1 +
>>> configs/ls2080aqds_nand_defconfig                |  1 +
>>> configs/ls2080ardb_SECURE_BOOT_defconfig         |  1 +
>>> configs/ls2080ardb_defconfig                     |  1 +
>>> configs/ls2080ardb_nand_defconfig                |  1 +
>>> configs/xilinx_zynqmp_ep_defconfig               |  1 +
>>> configs/xilinx_zynqmp_zc1751_xm015_dc1_defconfig |  1 +
>>> configs/xilinx_zynqmp_zc1751_xm016_dc2_defconfig |  1 +
>>> configs/xilinx_zynqmp_zc1751_xm019_dc5_defconfig |  1 +
>>> configs/xilinx_zynqmp_zcu102_defconfig           |  1 +
>>> configs/xilinx_zynqmp_zcu102_revB_defconfig      |  1 +
>>> include/efi_loader.h                             |  5 ++
>>> lib/efi_loader/Kconfig                           |  9 +++
>>> lib/efi_loader/efi_disk.c                        | 70 +++++++++++++++++++++---
>>> lib/efi_loader/efi_memory.c                      | 16 ++++++
>>> 18 files changed, 105 insertions(+), 9 deletions(-)
>>
> 
>