Another one I sent to bugs@ a while ago.
I'm assuming that having 'i386' in the original subject line made everyone hit
their 'd' key, without realizing that this affects amd64 too...
The patch below fixes an off-by-one in /arch/amd64/stand/libsa/cmd_i386.c.
The affected code path is handling the machine boot command in the bootloader.
Currently, trying to boot from MBR partition 'a', with a command such as
machine boot hd0a, will in fact boot from whichever partition is flagged as
active, rather than forcing a boot from partition 'a'.
The bug was introduced in revision 1.20 of the original i386 architecture file
over 20 years ago on 19980224.
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--- arch/amd64/stand/libsa/cmd_i386.c.dist Fri May 10 18:20:43 2019
+++ arch/amd64/stand/libsa/cmd_i386.c Sun Aug 15 23:44:45 2021
@@ -107,7 +107,7 @@
dev += (cmd.argv[1][2] - '0');
part = (cmd.argv[1][3] - 'a');
- if (part > 0)
+ if (part >= 0)
printf("[%x,%d]\n", dev, part);
else
printf("[%x]\n", dev);
@@ -119,7 +119,7 @@
goto bad;
/* Frob boot flag in buffer from HD */
- if ((dev & 0x80) && (part > 0)){
+ if ((dev & 0x80) && (part >= 0)){
int i, j;
for (i = 0, j = DOSPARTOFF; i < 4; i++, j += 16)
--- arch/i386/stand/libsa/cmd_i386.c.dist Fri Jun 10 15:36:06 2016
+++ arch/i386/stand/libsa/cmd_i386.c Sun Aug 15 23:44:23 2021
@@ -119,7 +119,7 @@
dev += (cmd.argv[1][2] - '0');
part = (cmd.argv[1][3] - 'a');
- if (part > 0)
+ if (part >= 0)
printf("[%x,%d]\n", dev, part);
else
printf("[%x]\n", dev);
@@ -131,7 +131,7 @@
goto bad;
/* Frob boot flag in buffer from HD */
- if ((dev & 0x80) && (part > 0)){
+ if ((dev & 0x80) && (part >= 0)){
int i, j;
for (i = 0, j = DOSPARTOFF; i < 4; i++, j += 16)
