Since you asked here is a little more info: The file's EFI_FILE_PROTOCOL is insufficient information to find it as it just contains the path in file system for the file. That's the equivalent to saying "I want to open file directory/foo.txt". you need to give more context for success.
To load into memory, it needs a EFI_DEVICE_PATH_PROTOCOL, this is a path to the device the file resides on, followed by the path in the file system for the file. In the UEFI Shell there is a "drive name" that is something like "fs0" which the shell decodes to get the first portion of the EFI_DEVICE_PATH_PROTOCOL for your file. You can look in ShellProtocol.c for 2 functions involved: EfiShellGetDevicePathFromFilePath, and EfiShellGetFilePathFromDevicePath (one for each direction of conversion). -Jaben > -----Original Message----- > From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of > Andrew Fish > Sent: Friday, February 05, 2016 6:56 AM > To: Michael Zimmermann <sigmaepsilo...@gmail.com> > Cc: edk2-devel@lists.01.org <edk2-de...@ml01.01.org>; Laszlo Ersek > <ler...@redhat.com> > Subject: Re: [edk2] manually booting efi file > > > > On Feb 5, 2016, at 6:44 AM, Michael Zimmermann > <sigmaepsilo...@gmail.com> wrote: > > > > Lazlo, > > > > using 'FileDevicePath' works perfectly, thx :) > > sth. else I stumbled on is this typedef: > > typedef EFI_DEVICE_PATH_PROTOCOL EFI_DEVICE_PATH; > > > > I tried to find a way to convert from EFI_DEVICE_PATH_PROTOCOL to > > EFI_DEVICE_PATH until I saw that it's just an alias :P > > > > Also EFI boots from removable media via spec defined file names. > So if you search for BOOTX64.EFI you find: > #define EFI_REMOVABLE_MEDIA_FILE_NAME_X64 > L"\\EFI\\BOOT\\BOOTX64.EFI" > That leads you to: > #define EFI_REMOVABLE_MEDIA_FILE_NAME > EFI_REMOVABLE_MEDIA_FILE_NAME_X64 > And that will point you to the BDS code that loads files from removable media: > > ~/work/src/edk2(master)>git grep EFI_REMOVABLE_MEDIA_FILE_NAME -- *.c > IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c:2081: > FullDevicePath = FileDevicePath (Handle, > EFI_REMOVABLE_MEDIA_FILE_NAME); > IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c:2376: > FilePath = FileDevicePath (Handle, EFI_REMOVABLE_MEDIA_FILE_NAME); > IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c:3336: > EFI_REMOVABLE_MEDIA_FILE_NAME, > IntelFrameworkModulePkg/Library/GenericBdsLib/BdsBoot.c:3720: > EFI_REMOVABLE_MEDIA_FILE_NAME, > MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c:1398: by appending > EFI_REMOVABLE_MEDIA_FILE_NAME. > MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c:1434: > TempDevicePath = FileDevicePath (Handle, > EFI_REMOVABLE_MEDIA_FILE_NAME); > MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c:1496: > TempDevicePath = FileDevicePath (SimpleFileSystemHandles[Index], > EFI_REMOVABLE_MEDIA_FILE_NAME); > MdeModulePkg/Universal/BdsDxe/BdsEntry.c:724: FilePath = FileDevicePath > (NULL, EFI_REMOVABLE_MEDIA_FILE_NAME); > Vlv2TbltDevicePkg/Library/PlatformBdsLib/BdsPlatform.c:1308: > EFI_REMOVABLE_MEDIA_FILE_NAME, > Vlv2TbltDevicePkg/Override/IntelFrameworkModulePkg/Library/GenericBdsL > ib/BdsBoot.c:2083: FullDevicePath = FileDevicePath (Handle, > EFI_REMOVABLE_MEDIA_FILE_NAME); > Vlv2TbltDevicePkg/Override/IntelFrameworkModulePkg/Library/GenericBdsL > ib/BdsBoot.c:2387: FilePath = FileDevicePath (Handle, > EFI_REMOVABLE_MEDIA_FILE_NAME); > Vlv2TbltDevicePkg/Override/IntelFrameworkModulePkg/Library/GenericBdsL > ib/BdsBoot.c:3351: EFI_REMOVABLE_MEDIA_FILE_NAME, > Vlv2TbltDevicePkg/Override/IntelFrameworkModulePkg/Library/GenericBdsL > ib/BdsBoot.c:3837: EFI_REMOVABLE_MEDIA_FILE_NAME, > > Thanks, > > Andrew Fish > > > > Thanks for everyone's help :) > > > > Michael > > > > On Fri, Feb 5, 2016 at 3:01 PM, Laszlo Ersek <ler...@redhat.com> wrote: > > > >> On 02/05/16 14:26, Michael Zimmermann wrote: > >>> The problem is that there is no GUID for 'EFI_FILE_PROTOCOL' there's > >>> only 'EFI_SIMPLE_FILE_SYSTEM_PROTOCOL' which I already have. > >> > >> Ah, sorry, I completely forgot about this. I've only ever worked with > >> EFI_SIMPLE_FILE_SYSTEM_PROTOCOL and EFI_FILE_PROTOCOL once, in git > >> commit 23d04b58e27b. > >> > >>> I don't even understand the concept of a devicepath attached to a file > >>> since a file is not a device. > >> > >> Okay, so I'm fuzzy on this, but the LoadImage() specification explains > >> it more or less. The idea is (/me hand-waving) that all but the last > >> device path nodes are used to locate the simple file system protocol > >> instance, and the last device path node, which is supposed to be of type > >> MEDIA_DEVICE_PATH, subtype MEDIA_FILEPATH_DP, carries the pathname > of > >> the file within the simple file system. > >> > >> The root directory of the file system would be opened with > >> EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.OpenVolume(), which returns an > >> EFI_FILE_PROTOCOL, standing for the root directory. > >> > >> This is in turn used with EFI_FILE_PROTOCOL.Open(), passing in the > >> pathname from MEDIA_FILEPATH_DP, to get the EFI_FILE_PROTOCOL that > >> ultimately stands for the file. > >> > >> So, what you need in this case is the following: > >> - the handle of the simple file system protocol that the file exists on > >> - the absolute pathname of the file within that file system. > >> > >> If you don't already have access to the first, I don't know how you can > >> get it, starting from EFI_FILE_PROTOCOL. > >> > >> The name of the file itself can be retrieved with > >> EFI_FILE_PROTOCOL.GetInfo(), passing in the EFI_FILE_INFO_ID GUID as > >> InformationType. However, I think this will only return the direct > >> filename, not the absolute pathname within the filesystem. So ultimately > >> I can't tell you how to get this piece of info either. > >> > >> Assuming you have them both though, you can use the FileDevicePath() > >> library function, from the DevicePathLib class > >> (MdePkg/Include/Library/DevicePathLib.h), to create a device path that > >> you can pass to LoadImage(). > >> > >> See also EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL. > >> > >> ... Hm, I think I just found an omission in the spec (2.6). > >> > >> Namely, in my first reply, I actually wanted to propose to load the > >> entire contents of the file into memory (using > >> EFI_FILE_PROTOCOL.Read()), and then pass the contents to LoadImage(), > >> using the SourceBuffer and SourceSize parameters. Also setting the > >> DevicePath parameter to NULL. > >> > >> Ultimately I didn't recommend this, because the spec doesn't mark the > >> DevicePath parameter of LoadImage() OPTIONAL. The LoadImage() > >> description *never* mentions that DevicePath can be NULL. This is the > >> omission. > >> > >> Because, if you look at EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL, it > says: > >> > >> [...] It is legal to call LoadImage() for a buffer in memory with a > >> NULL DevicePath parameter. In this case, the Loaded Image Device > >> Path Protocol is installed with a NULL interface pointer. > >> > >>> How do the Shell or other boot manager load such files? > >> > >> I don't think they ever start out with a bare EFI_FILE_PROTOCOL. But, > >> using the above method (load contents, pass buffer to LoadImage(), with > >> DevicePath=NULL), it should be possible. > >> > >> Sorry, I made a huge detour here. My only excuse is that the only time I > >> worked with this was long ago, and that the LoadImage() specification > >> seems incomplete. > >> > >> Thanks > >> Laszlo > >> > >>> On Fri, Feb 5, 2016 at 1:17 PM, Laszlo Ersek <ler...@redhat.com > >>> <mailto:ler...@redhat.com>> wrote: > >>> > >>> On 02/05/16 12:44, Michael Zimmermann wrote: > >>>> Hi, > >>>> > >>>> how can I boot a EFI application if I have it's > >> 'EFI_FILE_PROTOCOL'? > >>>> 'BdsStartEfiApplication' does only accept a 'EFI_DEVICE_PATH'. > >>> > >>> You could do the following: > >>> - call LocateHandle() to find all handles that have EFI_FILE_PROTOCOL > >>> installed > >>> - on each handle returned, call OpenProtocol() with GET_PROTOCOL > and > >>> the EFI_FILE_PROTOCOL GUID, and see if the returned protocol > >>> interface address matches the one that you already have > >>> - if so, call OpenProtocol() with GET_PROTOCOL and the > >>> EFI_DEVICE_PATH_PROTOCOL GUID on the same handle. > >>> > >>> Laszlo > >>> > >>>> > >>>> Michael > >>>> _______________________________________________ > >>>> edk2-devel mailing list > >>>> edk2-devel@lists.01.org <mailto:edk2-devel@lists.01.org> > >>>> https://lists.01.org/mailman/listinfo/edk2-devel > >>>> > >>> > >>> > >> > >> > > _______________________________________________ > > edk2-devel mailing list > > edk2-devel@lists.01.org > > https://lists.01.org/mailman/listinfo/edk2-devel > > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
