Re: how do I use RamDiskDxe?

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----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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