88ced6dd2f
Build x86 firmware from the tarball. Add 4 qemu-* firmware subpackages. (bnc#830002) OBS-URL: https://build.opensuse.org/request/show/199020 OBS-URL: https://build.opensuse.org/package/show/Virtualization/qemu?expand=0&rev=162
56 lines
2.2 KiB
Diff
56 lines
2.2 KiB
Diff
From 238050dfd46e3c4a87329da1d48b4d8dde5af8a1 Mon Sep 17 00:00:00 2001
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From: Michael Brown <mcb30@ipxe.org>
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Date: Fri, 7 Jun 2013 13:46:27 +0100
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Subject: [PATCH] [build] Work around bug in gcc >= 4.8
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gcc 4.8 and 4.9 fail to compile pxe_call.c with the error "bp cannot
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be used in asm here". Other points in the codebase which use "ebp" in
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the asm clobber list do not seem to be affected.
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Unfortunately gcc provides no way to specify %ebp as an output
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register, so we cannot use this as a workaround. The only viable
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solution is to explicitly push/pop %ebp within the asm itself. This
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is ugly for two reasons: firstly, it may be unnecessary; secondly, it
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may cause gcc to generate invalid %esp-relative addresses if the asm
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happens to use memory operands. This specific block of asm uses no
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memory operands and so will not generate invalid code.
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Reported-by: Daniel P. Berrange <berrange@redhat.com>
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Reported-by: Christian Hesse <list@eworm.de>
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Originally-fixed-by: Christian Hesse <list@eworm.de>
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Signed-off-by: Michael Brown <mcb30@ipxe.org>
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---
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roms/ipxe/src/arch/i386/interface/pxe/pxe_call.c | 8 +++++---
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1 file changed, 5 insertions(+), 3 deletions(-)
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Index: b/roms/ipxe/src/arch/i386/interface/pxe/pxe_call.c
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===================================================================
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--- a/roms/ipxe/src/arch/i386/interface/pxe/pxe_call.c
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+++ b/roms/ipxe/src/arch/i386/interface/pxe/pxe_call.c
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@@ -265,12 +265,14 @@ int pxe_start_nbp ( void ) {
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DBG ( "Restarting NBP (%x)\n", jmp );
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/* Far call to PXE NBP */
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- __asm__ __volatile__ ( REAL_CODE ( "movw %%cx, %%es\n\t"
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+ __asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t" /* gcc bug */
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+ "movw %%cx, %%es\n\t"
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"pushw %%es\n\t"
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"pushw %%di\n\t"
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"sti\n\t"
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"lcall $0, $0x7c00\n\t"
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- "addw $4, %%sp\n\t" )
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+ "popl %%ebp\n\t" /* discard */
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+ "popl %%ebp\n\t" /* gcc bug */ )
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: "=a" ( rc ), "=b" ( discard_b ),
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"=c" ( discard_c ), "=d" ( discard_d ),
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"=D" ( discard_D )
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@@ -278,7 +280,7 @@ int pxe_start_nbp ( void ) {
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"c" ( rm_cs ),
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"d" ( virt_to_phys ( &pxenv ) ),
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"D" ( __from_text16 ( &ppxe ) )
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- : "esi", "ebp", "memory" );
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+ : "esi", "memory" );
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return rc;
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}
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