Re: Getting GCC to target Windows RT

[Jeffrey Walton <noloader at gmail dot com>]

On Sun, Mar 17, 2013 at 7:52 AM, Nathan K. Ladwig (Netham45)
<netham45@gmail.com> wrote:
> I would like to begin work on getting GCC to target Windows RT (Windows on ARM)
>
> Here are the current relevant known details of the target:
> Uses PEs
> PEs seem to use the same header values as the x86 counterparts, except
> with the 'Machine type' field set to 0x01C4, instead of 0x014C (See
> http://i.imgur.com/KMjNuUF.png for more header information)
> Can use ARM code, but interrupt handlers will (incorrectly) throw the
> CPU back into THUMB mode upon return, therefore ARM code is highly
> unstable
> Because of this, THUMB2 is the preferred code format
>
> I admittedly have done very little work with GCC and I'm not 100% sure
> where I would start on porting it to target Windows RT. My main
> interest is to support desktop applications, which can be achieved
> with the jailbreak tool I maintain. My main goal is to get GCC running
> to aid development on the platform, I don't have a specific
> application in mind (though, I suppose that X-Chat would make a good
> test case, due to it's complexity).
>
> I've looked at 'cegcc', and I believe that CE is too far removed from
> Windows RT to be of any use, I believe that a better starting point
> would be to get the same GCC that targets x86/x64 Windows to target
> Windows on ARM.
>
> So, my main question is: Where do I start doing this?

There's lots of goodies in winnt.h. You might start by looking through
the header and getting a feel for the platform.

Below is from my copy of <winnt.h> located in C:\Program Files
(x86)\Windows Kits\8.0\Include\um\winnt.h (near line 14150). 0x01c4 is
defined.

I might have got it with my Visual Studio 2012 install; or from the
Windows Phone {7|8} SDK install. I did not check between installations
a few months back.

Jeff

#define IMAGE_FILE_MACHINE_UNKNOWN           0
#define IMAGE_FILE_MACHINE_I386              0x014c  // Intel 386.
#define IMAGE_FILE_MACHINE_R3000             0x0162  // MIPS
little-endian, 0x160 big-endian
#define IMAGE_FILE_MACHINE_R4000             0x0166  // MIPS little-endian
#define IMAGE_FILE_MACHINE_R10000            0x0168  // MIPS little-endian
#define IMAGE_FILE_MACHINE_WCEMIPSV2         0x0169  // MIPS
little-endian WCE v2
#define IMAGE_FILE_MACHINE_ALPHA             0x0184  // Alpha_AXP
#define IMAGE_FILE_MACHINE_SH3               0x01a2  // SH3 little-endian
#define IMAGE_FILE_MACHINE_SH3DSP            0x01a3
#define IMAGE_FILE_MACHINE_SH3E              0x01a4  // SH3E little-endian
#define IMAGE_FILE_MACHINE_SH4               0x01a6  // SH4 little-endian
#define IMAGE_FILE_MACHINE_SH5               0x01a8  // SH5
#define IMAGE_FILE_MACHINE_ARM               0x01c0  // ARM Little-Endian
#define IMAGE_FILE_MACHINE_THUMB             0x01c2  // ARM
Thumb/Thumb-2 Little-Endian
#define IMAGE_FILE_MACHINE_ARMNT             0x01c4  // ARM Thumb-2
Little-Endian
#define IMAGE_FILE_MACHINE_AM33              0x01d3
#define IMAGE_FILE_MACHINE_POWERPC           0x01F0  // IBM PowerPC
Little-Endian
#define IMAGE_FILE_MACHINE_POWERPCFP         0x01f1
#define IMAGE_FILE_MACHINE_IA64              0x0200  // Intel 64
#define IMAGE_FILE_MACHINE_MIPS16            0x0266  // MIPS
#define IMAGE_FILE_MACHINE_ALPHA64           0x0284  // ALPHA64
#define IMAGE_FILE_MACHINE_MIPSFPU           0x0366  // MIPS
#define IMAGE_FILE_MACHINE_MIPSFPU16         0x0466  // MIPS
#define IMAGE_FILE_MACHINE_AXP64             IMAGE_FILE_MACHINE_ALPHA64
#define IMAGE_FILE_MACHINE_TRICORE           0x0520  // Infineon
#define IMAGE_FILE_MACHINE_CEF               0x0CEF
#define IMAGE_FILE_MACHINE_EBC               0x0EBC  // EFI Byte Code
#define IMAGE_FILE_MACHINE_AMD64             0x8664  // AMD64 (K8)
#define IMAGE_FILE_MACHINE_M32R              0x9041  // M32R little-endian
#define IMAGE_FILE_MACHINE_CEE               0xC0EE