From: Helge Deller <deller@gmx.de>
To: qemu-devel@nongnu.org
Cc: Helge Deller <deller@gmx.de>,
Richard Henderson <richard.henderson@linaro.org>,
Richard Henderson <rth@twiddle.net>
Subject: [PATCH 7/7] target/hppa: Fix boot with old Linux installation CDs
Date: Tue, 1 Sep 2020 20:34:52 +0200 [thread overview]
Message-ID: <20200901183452.24967-8-deller@gmx.de> (raw)
In-Reply-To: <20200901183452.24967-1-deller@gmx.de>
The current qemu hppa emulation emulates a PA1.1 CPU, which can only execute
the 32-bit instruction set. For unknown 64-bit instructions, a instruction trap
is sent to the virtual CPU.
This behaviour is correct in the sense that we emulate what the PA1.1
specification says.
But when trying to boot older Linux installation images, e.g.
ftp://parisc.parisc-linux.org/debian-cd/debian-5.0/lenny-5.0.10-hppa-iso-cd/cdimage.debian.org/debian-5010-hppa-netinst.iso
one finds that qemu fails to boot those images.
The problem is, that in the Linux kernel (e.g. 2.6.26) of those old images
64-bit instructions were used by mistake in the fault handlers. The relevant
instructions (the ",*" indicates that it's a 64-bit instruction) I see are:
0: 09 3e 04 29 sub,* sp,r9,r9
0: 08 3d 06 3d add,* ret1,r1,ret1
0: 0a 09 02 61 or,* r9,r16,r1
0: 0a ba 00 3a andcm,* r26,r21,r26
0: 08 33 02 33 and,* r19,r1,r19
The interesting part is, that real physical 32-bit machines (like the 700/64
and B160L - which is the one we emulate) do boot those images and thus seem to
simply ignore the 64-bit flag on those instructions.
The patch below modifies the qemu instruction decoder to ignore the 64-bit flag
too - which is what real 32-bit hardware seems to do. With this modification
qemu now successfully boots those older images too.
I suggest to apply the patch below - even if it does not reflect what the SPEC
says. Instead it increases the compatibility to really existing hardware and
seem to not create problems if we add real PA2.0 support anytime later.
Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
target/hppa/insns.decode | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/target/hppa/insns.decode b/target/hppa/insns.decode
index f0dd71dd08..dceaad65e9 100644
--- a/target/hppa/insns.decode
+++ b/target/hppa/insns.decode
@@ -149,9 +149,9 @@ lci 000001 ----- ----- -- 01001100 0 t:5
# Arith/Log
####
-andcm 000010 ..... ..... .... 000000 0 ..... @rrr_cf
-and 000010 ..... ..... .... 001000 0 ..... @rrr_cf
-or 000010 ..... ..... .... 001001 0 ..... @rrr_cf
+andcm 000010 ..... ..... .... 000000 - ..... @rrr_cf
+and 000010 ..... ..... .... 001000 - ..... @rrr_cf
+or 000010 ..... ..... .... 001001 - ..... @rrr_cf
xor 000010 ..... ..... .... 001010 0 ..... @rrr_cf
uxor 000010 ..... ..... .... 001110 0 ..... @rrr_cf
ds 000010 ..... ..... .... 010001 0 ..... @rrr_cf
@@ -161,13 +161,13 @@ uaddcm_tc 000010 ..... ..... .... 100111 0 ..... @rrr_cf
dcor 000010 ..... 00000 .... 101110 0 ..... @rr_cf
dcor_i 000010 ..... 00000 .... 101111 0 ..... @rr_cf
-add 000010 ..... ..... .... 0110.. 0 ..... @rrr_cf_sh
+add 000010 ..... ..... .... 0110.. - ..... @rrr_cf_sh
add_l 000010 ..... ..... .... 1010.. 0 ..... @rrr_cf_sh
add_tsv 000010 ..... ..... .... 1110.. 0 ..... @rrr_cf_sh
add_c 000010 ..... ..... .... 011100 0 ..... @rrr_cf_sh0
add_c_tsv 000010 ..... ..... .... 111100 0 ..... @rrr_cf_sh0
-sub 000010 ..... ..... .... 010000 0 ..... @rrr_cf
+sub 000010 ..... ..... .... 010000 - ..... @rrr_cf
sub_tsv 000010 ..... ..... .... 110000 0 ..... @rrr_cf
sub_tc 000010 ..... ..... .... 010011 0 ..... @rrr_cf
sub_tsv_tc 000010 ..... ..... .... 110011 0 ..... @rrr_cf
--
2.21.3
next prev parent reply other threads:[~2020-09-01 18:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 18:34 [PATCH 0/7] hppa power button support, graphics updates and firmware fixes Helge Deller
2020-09-01 18:34 ` [PATCH 1/7] seabios-hppa: Update SeaBIOS to hppa-qemu-5.2-2 tag Helge Deller
2020-09-01 18:34 ` [PATCH 2/7] hw/hppa: Make number of TLB and BTLB entries configurable Helge Deller
2020-09-01 21:36 ` Richard Henderson
2020-09-02 11:16 ` Helge Deller
2020-09-02 16:52 ` Richard Henderson
2020-09-02 19:36 ` Helge Deller
2020-09-01 18:34 ` [PATCH 3/7] hw/hppa: Store boot device in fw_cfg section Helge Deller
2020-09-01 21:37 ` Richard Henderson
2020-09-01 18:34 ` [PATCH 4/7] hw/hppa: Inform SeaBIOS about fw_cfg port address Helge Deller
2020-09-01 21:39 ` Richard Henderson
2020-09-02 11:24 ` Helge Deller
2020-09-02 16:46 ` Richard Henderson
2020-09-02 19:37 ` Helge Deller
2020-09-01 18:34 ` [PATCH 5/7] hw/hppa: Add power button emulation Helge Deller
2020-09-01 21:42 ` Richard Henderson
2020-09-01 18:34 ` [PATCH 6/7] hw/display/artist: Fix artist screen resolution Helge Deller
2020-09-01 21:49 ` Richard Henderson
2020-09-02 21:48 ` Helge Deller
2020-09-02 22:09 ` Richard Henderson
2020-09-03 6:07 ` Helge Deller
2020-09-03 6:08 ` Helge Deller
2020-09-03 6:09 ` Helge Deller
2020-09-03 15:09 ` Richard Henderson
2020-09-01 18:34 ` Helge Deller [this message]
2020-09-01 19:37 ` [PATCH 0/7] hppa power button support, graphics updates and firmware fixes Philippe Mathieu-Daudé
2020-09-01 19:49 ` Helge Deller
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