__linux__ and cross-compile

Hi there,

The following patch fixes compilation/miscompilation problems, which may happend iwtg variuos cross compile configuration, wherte the compiler used to compile the kernel does not necessarily define __linux__. The patch replaces __linux__ with __KERNEL__, using __KERNEL_ as an indication that the source is compiled as a part of linux. Sources, which can be compiled in userspace as well, are changed to use #if defined(__linux__) || defined(__KERNEL__).

Regards,
-velco

===== arch/alpha/kernel/entry.S 1.1 vs edited =====

@@ -121,9 +121,6 @@
 
 .text
 .set noat
-#if defined(__linux__) && !defined(__ELF__)
-  .set singlegp
-#endif
 
 .align 3
 .globl	entInt

===== drivers/char/drm/drm.h 1.2 vs edited =====

@@ -35,7 +35,7 @@
 #ifndef _DRM_H_
 #define _DRM_H_
 
-#if defined(__linux__)
+#if defined(__linux__) || defined(__KERNEL__)
 #include <linux/config.h>
 #include <asm/ioctl.h>		/* For _IO* macros */
 #define DRM_IOCTL_NR(n)	     _IOC_NR(n)

===== drivers/char/drm-4.0/drm.h 1.1 vs edited =====

@@ -36,7 +36,7 @@
 #define _DRM_H_
 
 #include <linux/config.h>
-#if defined(__linux__)
+#if defined(__linux__) || defined(__KERNEL__)
 #include <asm/ioctl.h>		/* For _IO* macros */
 #define DRM_IOCTL_NR(n)	     _IOC_NR(n)
 #elif defined(__FreeBSD__)

===== drivers/scsi/aic7xxx/aic7xxx.c 1.1 vs edited =====

@@ -3653,7 +3653,7 @@
 	case 2:
 		ahc_dma_tag_destroy(ahc, ahc->shared_data_dmat);
 	case 1:
-#ifndef __linux__
+#ifndef __KERNEL__
 		ahc_dma_tag_destroy(ahc, ahc->buffer_dmat);
 #endif
 		break;

@@ -3661,7 +3661,7 @@
 		break;
 	}
 
-#ifndef __linux__
+#ifndef __KERNEL__
 	ahc_dma_tag_destroy(ahc, ahc->parent_dmat);
 #endif
 	ahc_platform_free(ahc);

@@ -4121,7 +4121,7 @@
 	newcount = MIN(newcount, (AHC_SCB_MAX_ALLOC - scb_data->numscbs));
 	for (i = 0; i < newcount; i++) {
 		struct scb_platform_data *pdata;
-#ifndef __linux__
+#ifndef __KERNEL__
 		int error;
 #endif
 		pdata = (struct scb_platform_data *)malloc(sizeof(*pdata),

@@ -4138,7 +4138,7 @@
 		next_scb->sg_list_phys = physaddr + sizeof(struct ahc_dma_seg);
 		next_scb->ahc_softc = ahc;
 		next_scb->flags = SCB_FREE;
-#ifndef __linux__
+#ifndef __KERNEL__
 		error = ahc_dmamap_create(ahc, ahc->buffer_dmat, /*flags*/0,
 					  &next_scb->dmamap);
 		if (error != 0)

@@ -4254,7 +4254,7 @@
 	if ((AHC_TMODE_ENABLE & (0x1 << ahc->unit)) == 0)
 		ahc->features &= ~AHC_TARGETMODE;
 
-#ifndef __linux__
+#ifndef __KERNEL__
 	/* DMA tag for mapping buffers into device visible space. */
 	if (ahc_dma_tag_create(ahc, ahc->parent_dmat, /*alignment*/1,
 			       /*boundary*/BUS_SPACE_MAXADDR_32BIT + 1,

===== drivers/scsi/aic7xxx/aic7xxx.h 1.1 vs edited =====

@@ -547,7 +547,7 @@
 	ahc_io_ctx_t		  io_ctx;
 	struct ahc_softc	 *ahc_softc;
 	scb_flag		  flags;
-#ifndef __linux__
+#ifndef __KERNEL__
 	bus_dmamap_t		  dmamap;
 #endif
 	struct scb_platform_data *platform_data;

@@ -870,7 +870,7 @@
 struct ahc_softc {
 	bus_space_tag_t           tag;
 	bus_space_handle_t        bsh;
-#ifndef __linux__
+#ifndef __KERNEL__
 	bus_dma_tag_t		  buffer_dmat;   /* dmat for buffer I/O */
 #endif
 	struct scb_data		 *scb_data;

===== drivers/scsi/dpt/osd_defs.h 1.1 vs edited =====

@@ -52,7 +52,7 @@
 /*Definitions - Defines & Constants ----------------------------------------- */
 
   /* Define the operating system */
-#if (defined(__linux__))
+#if defined(__linux__) || defined(__KERNEL__)
 # define _DPT_LINUX
 #elif (defined(__bsdi__))
 # define _DPT_BSDI

===== include/asm-mips/sgidefs.h 1.1 vs edited =====

@@ -11,14 +11,6 @@
 #define __ASM_SGIDEFS_H
 
 /*
- * Using a Linux compiler for building Linux seems logic but not to
- * everybody.
- */
-#ifndef __linux__
-#error Use a Linux compiler or give up.
-#endif
-
-/*
  * Definitions for the ISA levels
  *
  * With the introduction of MIPS32 / MIPS64 instruction sets definitions

===== include/asm-mips64/sgidefs.h 1.1 vs edited =====

@@ -11,14 +11,6 @@
 #define __ASM_SGIDEFS_H
 
 /*
- * Using a Linux compiler for building Linux seems logic but not to
- * everybody.
- */
-#ifndef __linux__
-#error Use a Linux compiler or give up.
-#endif
-
-/*
  * Definitions for the ISA levels
  *
  * With the introduction of MIPS32 / MIPS64 instruction sets definitions

===== include/linux/coda.h 1.1 vs edited =====

@@ -98,7 +98,7 @@
 #endif /* !DJGPP */
 
 
-#if defined(__linux__)
+#if defined(__linux__) || defined(__KERNEL__)
 #define cdev_t u_quad_t
 #ifndef __KERNEL__
 #if !defined(_UQUAD_T_) && (!defined(__GLIBC__) || __GLIBC__ < 2)

@@ -211,8 +211,8 @@
 #endif	/* VICEFID */
 
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__KERNEL__)
 static __inline__ ino_t  coda_f2i(struct ViceFid *fid)
 {
 	if ( ! fid ) 
 

Isn't this a compiler bug?

This is definitely wrong in files that are not Linux-specific and that are used on FreeBSD (and BSDI) as well (you would know that if you'd looked at the files your patch changes)...

cu
Adrian

Adrian> Isn't this a compiler bug?

Why would it be ? I may want to cross-compile from, e.g., NetBSD with the host compiler, or I may want compile from GNU/Linux, but with a compiler like arm-elf-gcc, that is, generic arm cross compiler, used for other kernels too.

Adrian> This is definitely wrong in files that are not Linux-specific and that are Adrian> used on FreeBSD (and BSDI) as well (you would know that if you'd looked at Adrian> the files your patch changes)...

*BSD define _KERNEL, don't they ?

Regards,
-velco

If your compiler is configured as a cross-compiler everything should work as expected. If you are trying to compile a Linux kernel with a gcc that is configured to build binaries for NetBSD this sounds evil.

I don't know (I never tried to compile a *BSD kernel).
But if yes please consider what the following parts of your patch change:

-#ifndef __linux__
+#ifndef __KERNEL__

cu
Adrian

Adrian> If your compiler is configured as a cross-compiler everything should work Adrian> as expected. If you are trying to compile a Linux kernel with a gcc that Adrian> is configured to build binaries for NetBSD this sounds evil.

Could you elaborate why ? I think people do it all the time, compiling linux (which is not a _linux_ binary, but a i386, alpha, etc. binary) with a compiler configured to compile linux binaries.

Adrian> This is definitely wrong in files that are not Linux-specific and that are Adrian> used on FreeBSD (and BSDI) as well (you would know that if you'd looked at Adrian> the files your patch changes)...

Adrian> I don't know (I never tried to compile a *BSD kernel). Adrian> But if yes please consider what the following parts of your patch change:

Adrian> -#ifndef __linux__
Adrian> +#ifndef __KERNEL__

I have. Have you ?

Regards,
-velco

What if he's trying to build UML to run on NetBSD? What if the best QA'd cross-gcc he has available is a generic arm-elf-gcc and he doesn't want to rebuild and do a full test and release cycle on it just because a handful of the kernel header files assume __linux__ will be defined?

If you don't know, who was it that typed 'This is definitely wrong' in your first mail? Your cat?

This is part of his patch to drivers/scsi/aic7xxx/aic7xxx.c

It's clear that code that is part of an "#ifndef __linux__" will never be included on any other OS than Linux. Is this also garuanteed for "#ifndef __KERNEL__"?

cu
Adrian

True. But unfortunately that's not a useful guarantee. This code doesn't (normally) run _on_ Linux. It is _in_ Linux, and it's still possible that the offending code won't get included when it should.

We think *BSD uses _KERNEL, and don't know of anything else which defines __KERNEL__ other than Linux. So he's switching from something that's known broken to something which we _believe_ will be reliable.

--
dwmw2