[U-Boot] [PATCH v3 8/8] cmd: env: add "-e" option for handling UEFI variables

AKASHI Takahiro
2018-12-19T01:49:16Z

Heinrich,

On Tue, Dec 18, 2018 at 07:07:02AM +0100, Heinrich Schuchardt wrote:
> On 12/18/18 6:05 AM, AKASHI Takahiro wrote:
> > "env [print|set] -e" allows for handling uefi variables without
> > knowing details about mapping to corresponding u-boot variables.
> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
>
> Hello Takahiro,
>
> in several patch series you are implementing multiple interactive
> commands that concern
>
> - handling of EFI variables
> - executing EFI binaries
> - managing boot sequence
>
> I very much appreciate your effort to provide an independent UEFI shell
> implementation. What I am worried about is that your current patches
> make it part of the monolithic U-Boot binary.

First of all, in v3, CONFIG_CMD_EFISHELL was introduced after Alex's
comment on v2. So you can disable efishell command if you don't want it.

Are you still worried?

> This design has multiple drawbacks:
>
> The memory size available for U-Boot is very limited for many devices.
> We already had to disable EFI_LOADER for some boards due to this
> limitations. Hence we want to keep everything out of the U-Boot binary
> that does not serve the primary goal of loading and executing the next
> binary.

I don't know your point here. If EFI_LOADER is disabled, efishell
will never be compiled in.

> The UEFI forum has published a UEFI Shell specification which is very
> extensive. We still have a lot of deficiencies in U-Boot's UEFI API
> implementation. By merging in parts of an UEFI shell implementation our
> project looses focus.

What is "our project?" What is "focus?"
I'm just asking as I want to share that information with you.

> There is an EDK2 implementation of said
> specification. If we fix the remaining bugs of the EFI API
> implementation in U-Boot we could simply run the EDK2 shell which
> provides all that is needed for interactive work.
>
> With you monolithic approach your UEFI shell implementation can neither
> be used with other UEFI API implementations than U-Boot nor can it be
> tested against other API implementations.

Let me explain my stance.
My efishell is basically something like a pursuit as well as
a debug/test tool which was and is still quite useful for me.
Without it, I would have completed (most of) my efi-related work so far.
So I believe that it will also be useful for other people who may want
to get involved and play with u-boot's efi environment.

I have never intended to fully implement a shell which is to be compliant
with UEFI specification while I'm trying to mimick some command
interfaces for convenience. UEFI shell, as you know, provides plenty
of "protocols" on which some UEFI applications, including UEFI SCT,
reply. I will never implement it with my efishell.

I hope that my efishell is a quick and easy way of learning more about
u-boot's uefi environment. I will be even happier if more people
get involved there.

> Due to these considerations I suggest that you build your UEFI shell
> implementation as a separate UEFI binary (like helloworld.efi). You may
> offer an embedding of the binary (like the bootefi hello command) into
> the finally linked U-Boot binary via a configuration variable. Please,
> put the shell implementation into a separate directory. You may want to
> designate yourself as maintainer (in file MAINTAINERS).

Yeah, your suggestion is reasonable and I have thought of it before.
There are, however, several reasons that I haven't done so; particularly,
efishell is implemented not only with boottime services but also
other helper functions, say, from device path utilities. Exporting them
as libraries is possible but I don't think that it would be so valuable.

Even if efishell is a separate application, it will not contribute to
reduce the total footprint if it is embedded along with u-boot binary.

Thanks,
-Takahiro Akashi

> Best regards
>
> Heinrich
>
>
> > ---
> > cmd/nvedit.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 59 insertions(+), 2 deletions(-)
> >
> > diff --git a/cmd/nvedit.c b/cmd/nvedit.c
> > index c0facabfc4fe..8168c963ac9d 100644
> > --- a/cmd/nvedit.c
> > +++ b/cmd/nvedit.c
> > @@ -27,6 +27,8 @@
> > #include <cli.h>
> > #include <command.h>
> > #include <console.h>
> > +#include <efi.h>
> > +#include <efi_loader.h>
> > #include <environment.h>
> > #include <search.h>
> > #include <errno.h>
> > @@ -119,6 +121,25 @@ static int do_env_print(cmd_tbl_t *cmdtp, int flag, int argc,
> > int rcode = 0;
> > int env_flag = H_HIDE_DOT;
> >
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 'e') {
> > + efi_status_t r;
> > +
> > + argc--;
> > + argv++;
> > +
> > + /* Initialize EFI drivers */
> > + r = efi_init_obj_list();
> > + if (r != EFI_SUCCESS) {
> > + printf("Error: Cannot set up EFI drivers, r = %lu\n",
> > + r & ~EFI_ERROR_MASK);
> > + return CMD_RET_FAILURE;
> > + }
> > +
> > + return do_efi_dump_var(argc, argv);
> > + }
> > +#endif
> > +
> > if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 'a') {
> > argc--;
> > argv++;
> > @@ -216,6 +237,26 @@ static int _do_env_set(int flag, int argc, char * const argv[], int env_flag)
> > ENTRY e, *ep;
> >
> > debug("Initial value for argc=%d\n", argc);
> > +
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 'e') {
> > + efi_status_t r;
> > +
> > + argc--;
> > + argv++;
> > +
> > + /* Initialize EFI drivers */
> > + r = efi_init_obj_list();
> > + if (r != EFI_SUCCESS) {
> > + printf("Error: Cannot set up EFI drivers, r = %lu\n",
> > + r & ~EFI_ERROR_MASK);
> > + return CMD_RET_FAILURE;
> > + }
> > +
> > + return do_efi_set_var(argc, argv);
> > + }
> > +#endif
> > +
> > while (argc > 1 && **(argv + 1) == '-') {
> > char *arg = *++argv;
> >
> > @@ -1262,15 +1303,23 @@ static char env_help_text[] =
> > #if defined(CONFIG_CMD_IMPORTENV)
> > "env import [-d] [-t [-r] | -b | -c] addr [size] [var ...] - import environment\n"
> > #endif
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + "env print [-a | -e [name] | name ...] - print environment\n"
> > +#else
> > "env print [-a | name ...] - print environment\n"
> > +#endif
> > #if defined(CONFIG_CMD_RUN)
> > "env run var [...] - run commands in an environment variable\n"
> > #endif
> > #if defined(CONFIG_CMD_SAVEENV) && !defined(CONFIG_ENV_IS_NOWHERE)
> > "env save - save environment\n"
> > #endif
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + "env set [-e | -f] name [arg ...]\n";
> > +#else
> > "env set [-f] name [arg ...]\n";
> > #endif
> > +#endif
> >
> > U_BOOT_CMD(
> > env, CONFIG_SYS_MAXARGS, 1, do_env,
> > @@ -1295,6 +1344,10 @@ U_BOOT_CMD_COMPLETE(
> > printenv, CONFIG_SYS_MAXARGS, 1, do_env_print,
> > "print environment variables",
> > "[-a]\n - print [all] values of all environment variables\n"
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + "printenv -e [<name>]\n"
> > + " - print UEFI variable 'name' or all the variables\n"
> > +#endif
> > "printenv name ...\n"
> > " - print value of environment variable 'name'",
> > var_complete
> > @@ -1322,7 +1375,11 @@ U_BOOT_CMD_COMPLETE(
> > U_BOOT_CMD_COMPLETE(
> > setenv, CONFIG_SYS_MAXARGS, 0, do_env_set,
> > "set environment variables",
> > - "[-f] name value ...\n"
> > +#if defined(CONFIG_CMD_EFISHELL)
> > + "-e <name> [<value>]\n"
> > + " - set UEFI variable 'name' to 'value' ...'\n"
> > +#endif
> > + "setenv [-f] name value ...\n"
> > " - [forcibly] set environment variable 'name' to 'value ...'\n"
> > "setenv [-f] name\n"
> > " - [forcibly] delete environment variable 'name'",
> > @@ -1343,7 +1400,7 @@ U_BOOT_CMD(
> > U_BOOT_CMD_COMPLETE(
> > run, CONFIG_SYS_MAXARGS, 1, do_run,
> > "run commands in an environment variable",
> > -#if defined(CONFIG_CMD_BOOTEFI)
> > +#if defined(CONFIG_CMD_EFISHELL)
> > "var -e [BootXXXX]\n"
> > " - load and run UEFI app based on 'BootXXXX' UEFI variable",
> > #else
> >
>