Re: how do I use RamDiskDxe?

[Rick Warner <rick@microway.com>]

On 02/13/18 19:48, Wu, Hao A wrote:
>> -----Original Message-----
>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Rick
>> Warner
>> Sent: Wednesday, February 14, 2018 12:33 AM
>> To: Wu, Hao A; Andrew Fish
>> Cc: edk2-devel@lists.01.org
>> Subject: Re: [edk2] how do I use RamDiskDxe?
>>
>> 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?
> For example, on OVMF, you can enter the setup page by executing 'exit'
> under shell. Then navigate through:
> 'Device Manager' ->
> 'RAM Disk Configuration'
>
> If you create a Ram disk from a file, the whole content of the file will
> be copied to the memory range when creating the Ram disk. The file can be
> an ISO image ,for example. In such case, after creating the Ram disk, a
> file system can be accessed on the Ram disk.
>
> Best Regards,
> Hao Wu
>
>> Thanks,
>> Rick Warner
>>
>>
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Thanks for the help on this.  I've achieved success.  My final solution
was to include the contents of RamDiskDxe.efi in an array and then use a
modified version of the load command (shell builtin) to load that memory
region as a driver image with LoadImage.  Once that is loaded, I created
another shell builtin that gets the Hii handle for it, works it's way to
the ConfigAccess method and then calls it to set the size and type. 
Finally, I modified the RamDiskDxe driver itself to initialize a raw
ramdisk with a FAT16 table.

I can now network boot my custom EFI shell and create a ram disk with no
other storage present in the system and then use that ramdisk to store
data/apps downloaded with tftp.

Thanks for getting me in the right direction with the Hii form stuff.

Rick