Date: Wed, 21 Jul 2010 15:00:28 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Nathan Whitehorn <nwhitehorn@freebsd.org> Cc: amd64@freebsd.org, freebsd-arch@freebsd.org Subject: Re: uname -m/-p for compat32 binaries Message-ID: <20100721120028.GM2381@deviant.kiev.zoral.com.ua> In-Reply-To: <4C460BB9.1060009@freebsd.org> References: <20100719213054.GB2381@deviant.kiev.zoral.com.ua> <201007200907.24715.jhb@freebsd.org> <4C460BB9.1060009@freebsd.org>
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On Tue, Jul 20, 2010 at 03:48:57PM -0500, Nathan Whitehorn wrote:
> On 07/20/10 08:07, John Baldwin wrote:
> >On Monday, July 19, 2010 5:30:54 pm Kostik Belousov wrote:
> >
> >>Hi,
> >>I intend to commit the following change, that makes sysctls
> >>hw.machine_arch and hw.machine to return "i386" for 32 bit
> >>binaries run on amd64. In particular, 32 bit uname -m and uname -p
> >>print "i386", that is good for i386 jails on amd64 kernels.
> >>
> >>I find the change very useful for me, but I wonder why such trivial
> >>modification is not yet done. Can anybody note a possible fallout from
> >>it ?
> >>
> >Presumably ia64 and powerpc64 would need a similar change as well? It
> >looks
> >fine to me. I suspect Y! used the UNAME_* approach as it didn't add yet-
> >another local diff to maintain in the kernel, and the uname fixes at Y!
> >might
> >have predated SCTL_MASK32.
> >
> Maybe it makes sense to define a MACHINE_ARCH32 in machine/param.h, as
> is done for ELF_ARCH32 in machine/elf.h? This would keep the MI code in
> the kernel MI, and ever-so-slightly simplify implementation for ia64,
> mips, and powerpc64. Thanks for doing this!
See below. Also, I painted red another wall, adding a sysctl to turn
the adaptive behaviour off.
diff --git a/sys/amd64/amd64/identcpu.c b/sys/amd64/amd64/identcpu.c
index 52e7568..914f4d2 100644
--- a/sys/amd64/amd64/identcpu.c
+++ b/sys/amd64/amd64/identcpu.c
@@ -76,8 +76,28 @@ static void print_via_padlock_info(void);
int cpu_class;
char machine[] = "amd64";
-SYSCTL_STRING(_hw, HW_MACHINE, machine, CTLFLAG_RD,
- machine, 0, "Machine class");
+
+extern int adaptive_machine_arch;
+
+static int
+sysctl_hw_machine(SYSCTL_HANDLER_ARGS)
+{
+#ifdef SCTL_MASK32
+ static const char machine32[] = "i386";
+#endif
+ int error;
+
+#ifdef SCTL_MASK32
+ if ((req->flags & SCTL_MASK32) != 0 && adaptive_machine_arch)
+ error = SYSCTL_OUT(req, machine32, sizeof(machine32));
+ else
+#endif
+ error = SYSCTL_OUT(req, machine, sizeof(machine));
+ return (error);
+
+}
+SYSCTL_PROC(_hw, HW_MACHINE, machine, CTLTYPE_STRING | CTLFLAG_RD,
+ NULL, 0, sysctl_hw_machine, "A", "Machine class");
static char cpu_model[128];
SYSCTL_STRING(_hw, HW_MODEL, model, CTLFLAG_RD,
diff --git a/sys/amd64/include/param.h b/sys/amd64/include/param.h
index c940597..9a742f9 100644
--- a/sys/amd64/include/param.h
+++ b/sys/amd64/include/param.h
@@ -59,6 +59,9 @@
#ifndef MACHINE_ARCH
#define MACHINE_ARCH "amd64"
#endif
+#ifndef MACHINE_ARCH32
+#define MACHINE_ARCH32 "i386"
+#endif
#if defined(SMP) || defined(KLD_MODULE)
#define MAXCPU 32
diff --git a/sys/ia64/include/param.h b/sys/ia64/include/param.h
index ba26290..36b27e0 100644
--- a/sys/ia64/include/param.h
+++ b/sys/ia64/include/param.h
@@ -57,6 +57,9 @@
#ifndef MACHINE_ARCH
#define MACHINE_ARCH "ia64"
#endif
+#ifndef MACHINE_ARCH32
+#define MACHINE_ARCH32 "i386"
+#endif
#if defined(SMP) || defined(KLD_MODULE)
#define MAXCPU 32
diff --git a/sys/kern/kern_mib.c b/sys/kern/kern_mib.c
index 7ef580f..3bfecea 100644
--- a/sys/kern/kern_mib.c
+++ b/sys/kern/kern_mib.c
@@ -232,9 +232,28 @@ sysctl_hw_pagesizes(SYSCTL_HANDLER_ARGS)
SYSCTL_PROC(_hw, OID_AUTO, pagesizes, CTLTYPE_ULONG | CTLFLAG_RD,
NULL, 0, sysctl_hw_pagesizes, "LU", "Supported page sizes");
-static char machine_arch[] = MACHINE_ARCH;
-SYSCTL_STRING(_hw, HW_MACHINE_ARCH, machine_arch, CTLFLAG_RD,
- machine_arch, 0, "System architecture");
+int adaptive_machine_arch = 1;
+static int
+sysctl_hw_machine_arch(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+ static const char machine_arch[] = MACHINE_ARCH;
+#ifdef SCTL_MASK32
+ static const char machine_arch32[] = MACHINE_ARCH32;
+
+ if ((req->flags & SCTL_MASK32) != 0 && adaptive_machine_arch)
+ error = SYSCTL_OUT(req, machine_arch32, sizeof(machine_arch32));
+ else
+#endif
+ error = SYSCTL_OUT(req, machine_arch, sizeof(machine_arch));
+ return (error);
+
+}
+SYSCTL_PROC(_hw, HW_MACHINE_ARCH, machine_arch, CTLTYPE_STRING | CTLFLAG_RD,
+ NULL, 0, sysctl_hw_machine_arch, "A", "System architecture");
+SYSCTL_INT(_debug, OID_AUTO, adaptive_machine_arch, CTLFLAG_RW,
+ &adaptive_machine_arch, 1,
+ "Adapt reported machine architecture to the ABI of the binary");
static int
sysctl_hostname(SYSCTL_HANDLER_ARGS)
diff --git a/sys/powerpc/include/param.h b/sys/powerpc/include/param.h
index 4aeabe7..91bb238 100644
--- a/sys/powerpc/include/param.h
+++ b/sys/powerpc/include/param.h
@@ -61,6 +61,11 @@
#endif
#endif
#define MID_MACHINE MID_POWERPC
+#ifdef __powerpc64__
+#ifndef MACHINE_ARCH32
+#define MACHINE_ARCH32 "powerpc"
+#endif
+#endif
#if defined(SMP) || defined(KLD_MODULE)
#define MAXCPU 2
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