On 4/10/21 2:35 PM, Sughosh Ganu wrote:
hi Heinrich,
For the last one day, i was debugging an issue which i encountered when
I tried to print the uefi env variables. This was seen both on arm64 and
arm32 platforms. I have sent a patch for this fix[1].
However, the reason i am writing to you is that, while i was debugging,
i was looking at the functionality of the EFI_CALL macro, along with
EFI_ENTRY AND EFI_EXIT. And i must admit that looking at the function
names and symbol names was a bit confusing. This is because it is kind
of difficult to guess the reference from which these symbols and
functions are named.
One example is the EFI_CALL macro, in which before the function is
called, there is an assert check for __efi_exit_check. Once the function
call returns, the assert check is for __efi_entry_check. This seems a
bit counter-intuitive -- the call made at EFI_CALL beginning is named
__efi_exit* and the one after the function return is named __efi_entry*.
Same goes for the pointer names used for holding the gd values. There is
an app_gd, and efi_gd. It is not very clear as to which is used where.
EFI_ENTRY() is used wherever an API call enters the firmware.
EFI_EXIT() is used wherever the firmware is left into the UEFI world.
EFI_CALL() replaces the sequence EFI_EXIT, function invocation, EFI_ENTRY.
app_gd is register r9/x18 of the UEFI world.
efi_gd is register r9/x18 of U-Boot.
I see that you are the original author of the EFI_MACRO call, and thus
EFI_CALL() was introduced by Rob Clark in a095aadffa9.
would be having a pretty good understanding of the nomenclature as well.
So, given how much you trouble me during code review(pun intended :P), I
was thinking to ask you for a favour. I was thinking if we can have a
document which explains these macros, api's and gd pointers in a little
detail. Can you please write such a document whenever you get time so
that it would be useful for people like me. Thanks for your time and
dedication to the u-boot project.
-sughosh
[1] - https://lists.denx.de/pipermail/u-boot/2021-April/446948.html
<https://lists.denx.de/pipermail/u-boot/2021-April/446948.html>
I can create such a document.
Best regards
Heinrich
