Re: how do I use RamDiskDxe?

[Rick Warner <rick@microway.com>]

On 02/12/2018 10:05 PM, Wu, Hao A wrote:
>> -----Original Message-----
>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>> Andrew Fish
>> Sent: Tuesday, February 13, 2018 8:40 AM
>> To: Rick Warner
>> Cc: edk2-devel@lists.01.org
>> Subject: Re: [edk2] how do I use RamDiskDxe?
>>
>>
>>
>>> On Feb 12, 2018, at 1:07 PM, Rick Warner <rick@microway.com> wrote:
>>>
>>> Hi All,
>>>
>>> I'm trying to develop a tool for automated BIOS flashing from the EFI shell
>> using IPMI serial over lan to drive it.  To accomplish this, my plan is to use a
>> network booted EFI shell with a tftp client and a ramdisk to download the flash
>> tools and ROM into as a workspace and then run the flash commands from that
>> ram disk.
>>> I've been able to successfully build and boot an efi shell from the edk 2
>> sources including the tftp client.  I've also been able to separately build the
>> RamDiskDxe driver from the MdeModulePkg. Loading the RamDiskDxe.efi
>> driver file results in a successful message, but I do not get any usable ram disk
>> made available to me?
>>> How do I get a usable drive letter/name (ie blk0: or any other name) from the
>> RamDiskDxe driver?
>> Looks like when you load the RamDiskDxe it registers gEfiRamDiskProtocolGuid
>> https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Protocol/Ra
>> mDisk.h
>> <https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Protocol/Ra
>> mDisk.h> which notes this API was added in UEFI 2.6 so you can read up on it in
>> that version of the EFI Spec.
>>
>>  From a quick site read of the code it looks like the driver just produces a
>> Protocol that lets you create a RAM disk and VRF (Setup Pages) that let you
>> configure one. Seems like you still need to call it and give the raw disk image.
>>
>
>
>>> Once I've done that, will it be possible to include the RamDiskDxe driver as
>> part of the network bootable efi shell image?  I assume I'll need to modify
>> the .dsc file for the ShellPkg to include the MdeModulePkg pieces.
>>> If anyone has any other suggestions for this, I'm open to ideas. The only way
>> I've been successful in network booting EFI shell is using just that file directly.  I
>> tried creating a dos filesystem image with the efi shell file in it just like would
>> work with a USB key, but that would not boot over the network stack. If there is
>> some way of creating a network bootable EFI shell filesystem image (similar to
>> how Linux can network boot a separate vmlinuz kernel and initrd image)?
>>> Are there any docs that I've missed (I've tried looking in the user docs and on
>> the wiki) regarding setting up RamDiskDxe?
>> Traditionally network booting has involved loading a single file over the
>> network (like an OS Loader) and that file uses the UEFI networking stack to
>> download (TFTP read) more images (like the Kernel) from a location implied by
>> the location used to download the single file (OS Loader).
>>
> Hi,
>
> For the RamDiskDxe part:
>
> Just as the previous reply, the RamDiskDxe driver provides:
> a). A protocol to (un)register a range of memory to a Ram disk
> b). A setup page for user to create:
>      a raw Ram disk (no data on the created one) or,
>      from a selected file (the file will be the content in the Ram disk,
>      no file system though)
>
> If you want to place the flash tools in the Ram disk and use it, I think
> you also need to format the Ram disk and create file system on it first
> (e.g. FAT).
>
> Best Regards,
> Hao Wu
>
>> Thanks,
>>
>> Andrew Fish

Thank you both very much!

How do I use the setup page to create either a raw (empty) or filled w/ 
a file ramdisk?  How do I call that?  I assume the file to create it 
from would need to already be local to the system.  Is that correct? Or 
would I be able to directly pull a filesystem image from tftp into the 
ramdisk upon creation?

Thanks,
Rick Warner