On 02/12/2018 10:05 PM, Wu, Hao A wrote:
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-boun...@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 <r...@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 
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
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 
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).


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


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?

Rick Warner

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