[PATCH] rombios: prevent building with PIC

[PATCH] rombios: prevent building with PIC

[Olaf Hering]

If the default compiler silently defaults to to -fPIC/-fPIE building
rombios fails:

 ld -melf_i386 -s -r 32bitbios.o tcgbios/tcgbiosext.o util.o pmm.o -o 32bitbios_all.o
 There are undefined symbols in the BIOS:
          U _GLOBAL_OFFSET_TABLE_
 make[10]: *** [Makefile:26: 32bitbios_all.o] Error 11

Prevent the failure by enforcing non-PIC mode.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---

build tested with staging-4.9.

PIE is the default now in openSUSE Tumbleweed:
https://lists.opensuse.org/opensuse-factory/2017-06/msg00403.html

 tools/firmware/rombios/32bit/Makefile         | 2 +-
 tools/firmware/rombios/32bit/tcgbios/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/firmware/rombios/32bit/Makefile b/tools/firmware/rombios/32bit/Makefile
index b0583c93df..97657ae7b1 100644
--- a/tools/firmware/rombios/32bit/Makefile
+++ b/tools/firmware/rombios/32bit/Makefile
@@ -3,7 +3,7 @@ include $(XEN_ROOT)/tools/firmware/Rules.mk
 
 TARGET = 32bitbios_flat.h
 
-CFLAGS += $(CFLAGS_xeninclude) -I.. -I../../../libacpi
+CFLAGS += $(CFLAGS_xeninclude) -I.. -I../../../libacpi -fno-pic
 
 SUBDIRS = tcgbios
 
diff --git a/tools/firmware/rombios/32bit/tcgbios/Makefile b/tools/firmware/rombios/32bit/tcgbios/Makefile
index f87d13020f..2e3729910f 100644
--- a/tools/firmware/rombios/32bit/tcgbios/Makefile
+++ b/tools/firmware/rombios/32bit/tcgbios/Makefile
@@ -3,7 +3,7 @@ include $(XEN_ROOT)/tools/firmware/Rules.mk
 
 TARGET  = tcgbiosext.o
 
-CFLAGS += $(CFLAGS_xeninclude) -I.. -I../.. -I../../../../libacpi
+CFLAGS += $(CFLAGS_xeninclude) -I.. -I../.. -I../../../../libacpi -fno-pic
 
 .PHONY: all
 all: $(TARGET)

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Re: [PATCH] rombios: prevent building with PIC

[Wei Liu]

On Fri, Jun 23, 2017 at 07:26:01PM +0200, Olaf Hering wrote:
> If the default compiler silently defaults to to -fPIC/-fPIE building
> rombios fails:
> 
>  ld -melf_i386 -s -r 32bitbios.o tcgbios/tcgbiosext.o util.o pmm.o -o 32bitbios_all.o
>  There are undefined symbols in the BIOS:
>           U _GLOBAL_OFFSET_TABLE_
>  make[10]: *** [Makefile:26: 32bitbios_all.o] Error 11
> 
> Prevent the failure by enforcing non-PIC mode.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>

Do you need to check if the compiler supports -fno-pic?

I know not every version of gcc support -fno-pie, but I'm not sure about
-fno-pic. In any case, there is already something in our build system to
deal with testing gcc options, which would be useful to you.

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Re: [PATCH] rombios: prevent building with PIC

[Olaf Hering]

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On Fri, Jun 23, Wei Liu wrote:

> Do you need to check if the compiler supports -fno-pic?

In my testing gcc-4.3 and 4.5 know about this option.

Olaf

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Re: [PATCH] rombios: prevent building with PIC

[Wei Liu]

On Fri, Jun 23, 2017 at 07:40:36PM +0200, Olaf Hering wrote:
> On Fri, Jun 23, Wei Liu wrote:
> 
> > Do you need to check if the compiler supports -fno-pic?
> 
> In my testing gcc-4.3 and 4.5 know about this option.
> 

We support >=4.1. Please check those as well.

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Re: [PATCH] rombios: prevent building with PIC

[Olaf Hering]

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On Fri, Jun 23, Wei Liu wrote:

> We support >=4.1. Please check those as well.

According to the PDF manuals at https://gcc.gnu.org/onlinedocs/ a
"-fno-foo" is mentioned, so I think -fno-pic is recognized. I will see
if I find a copy of SLE10 to verify with 4.1.2.


Olaf

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Re: [PATCH] rombios: prevent building with PIC

[Olaf Hering]

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On Fri, Jun 23, Wei Liu wrote:

> We support >=4.1. Please check those as well.

Yes, 4.1.2 works as well.

Olaf

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Re: [PATCH] rombios: prevent building with PIC

[Jan Beulich]

>>> Olaf Hering <olaf@aepfle.de> 06/23/17 7:27 PM >>>
>--- a/tools/firmware/rombios/32bit/Makefile
>+++ b/tools/firmware/rombios/32bit/Makefile
>@@ -3,7 +3,7 @@ include $(XEN_ROOT)/tools/firmware/Rules.mk
 >
 >TARGET = 32bitbios_flat.h
 >
>-CFLAGS += $(CFLAGS_xeninclude) -I.. -I../../../libacpi
>+CFLAGS += $(CFLAGS_xeninclude) -I.. -I../../../libacpi -fno-pic
 
In the description you also talk about PIE, but you deal with PIC only here. Is
that intentional? If so, please say why in the description.

Also, as to the Cc list - maintainership of rombios/ has recently changed.

Jan


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Re: [PATCH] rombios: prevent building with PIC

[Olaf Hering]

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Am Mon, 26 Jun 2017 00:30:50 -0600
schrieb "Jan Beulich" <jbeulich@suse.com>:

> In the description you also talk about PIE, but you deal with PIC only here. Is that intentional? If so, please say why in the description.

Thats what the URL says. Unclear what the connection between -fpic and -fPIE (?) is.

> Also, as to the Cc list - maintainership of rombios/ has recently changed.

Thats what --to-cmd=scripts/getmaintainer.pl gives me.

Olaf

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Re: [PATCH] rombios: prevent building with PIC

[Jan Beulich]

>>> Olaf Hering <olaf@aepfle.de> 06/26/17 8:47 AM >>>
>Am Mon, 26 Jun 2017 00:30:50 -0600
>schrieb "Jan Beulich" <jbeulich@suse.com>:
>
>> In the description you also talk about PIE, but you deal with PIC only here. Is that intentional? If so, please say why in the description.
>
>Thats what the URL says. Unclear what the connection between -fpic and -fPIE (?) is.

Unlike PIC, PIE was introduced later, yet might still be defaulted to. Hence it may
be necessary to also deal with that, instead of just addressing one half. Yet it
would mean detecting PIE support in the compiler, other than PIC, which - as
you've verified - is available everywhere we care about.

>> Also, as to the Cc list - maintainership of rombios/ has recently changed.
>
>Thats what --to-cmd=scripts/getmaintainer.pl gives me.

In the unstable staging tree? That would seem wrong.

Jan


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Re: [PATCH] rombios: prevent building with PIC

[Olaf Hering]

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Am Mon, 26 Jun 2017 05:55:17 -0600
schrieb "Jan Beulich" <jbeulich@suse.com>:

> Unlike PIC, PIE was introduced later, yet might still be defaulted to. Hence it may be necessary to also deal with that, instead of just addressing one half.

There is now v2 which uses cc-option-add

> In the unstable staging tree? That would seem wrong.

I ran git send-email from staging-4.9. Sorry for that.
Perhaps MAINTAINER changes should be merged unconditional into staging-x.y

Olaf

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