[Bug ld/30144] LD --entry does not accept function name

[pali at kernel dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30144

--- Comment #2 from Pali Rohár <pali at kernel dot org> ---
As a workaround I have already come up with this:

__attribute__((stdcall)) long DriverEntry(void *DriverObject, void
*RegistryPath) asm("DriverEntry");
__attribute__((stdcall)) long DriverEntry(void *DriverObject, void
*RegistryPath) {
    return 0;
}

And then you can use -Wl,--entry=DriverEntry for both AMD64 and IX86 archs.

Via asm keyword in function declaration you can specify symbol name of the
function itself.

And because entry point symbol is basically used only by linker for filling
base address field in PE binary, it can be anything.

But this is still a workaround because it is not practical to add #ifdef for
GNU tools into source code. Specially when MS tools do not need any special
arch dependent command line switch or #ifdef. Switch /ENTRY:DriverEntry works
for both AMD64 and IX86.


I thought that it could be relatively easy for PE IX86 version of LD to search
for symbol _XYZ@number when symbol XYZ specified in --entry does not exist.
Specially because there is some logic related to this (--kill-at). But I have
not looked at source code, so this was just my speculation...

Another option would be to implement switch to instruct gcc (or ld) to "compile
NT kernel driver" (I created issue for it:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108852) and part of it for IX86
platform could be automatic passing of --entry=_DriverEntry@8.

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