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From: "Ayush Singh" <ayushdevel1325@gmail.com>
Date: Thu, 16 Jun 2022 19:50:47 +0530
Message-ID: <CA+Yfj7uso=LosjTwsDe6NfbVaj7xe=GfavXMXF_Or3S+Cv6-vQ@mail.gmail.com>
Subject: Does edk2 also link to crt0-efi like GNU-EFI
To: edk2-devel-groups-io <devel@edk2.groups.io>
Cc: Michael Kubacki <mikuback@linux.microsoft.com>, michael.d.kinney@intel.com, 
	Jiewen Yao <jiewen.yao@intel.com>, jabeena.b.gaibusab@intel.com
Content-Type: text/plain; charset="UTF-8"

Hello everyone, I wanted to ask if the edk2 build system also links to
crt0-efi, like GNU-EFI?

If yes, I would also like to see how that is actually implemented. If
not, how does edk2 support custom entry functions? It is possible with
llvm backend but I am not sure how it is done in GCC and am curious,

Currently, rust does not support the custom implementation of
`lang_start` (which is started by crt0 in most platforms), so I was
trying to find ways to be able to use custom crt0 which sets up
`SystemTable` and `SystemHandler` and start the `lang_start` from it.
This way, the user will be able to call the normal `main` function
rather than using the `no_main` feature.

My blog post [1] shows how we currently use the `efi_main` function.

Yours sincerely,
Ayush Singh

[1]: (https://www.programmershideaway.xyz/post5/)