Re: [PATCH V3 1/2] kvm tools: Add ability to map guest RAM from hugetlbfs

[Matt Evans <matt@ozlabs.org>]

On 14/12/11 11:03, David Evensky wrote:
> 
> 
> On an x86 32bit system (and using the 32bit CodeSourcery toolchain on a x86_64 system) I get:
> 
> evensky@machine:~/.../linux-kvm/tools/kvm$ make
>   CC       util/util.o
> util/util.c: In function 'mmap_hugetlbfs':
> util/util.c:93:17: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
> util/util.c:99:7: error: format '%ld' expects argument of type 'long int', but argument 2 has type 'int' [-Werror=format]
> cc1: all warnings being treated as errors
> 
> make: *** [util/util.o] Error 1

Hi David,


Argh!  I didn't catch this as it compiles fine on my x86_64 box (with 64bit
toolchain) >:( So, struct statfs's f_type and f_blocks are __SWORD_TYPE which is
either an int or a long (if on 64bit).... so identical to if it were simply a
long, nice.

Pekka, a re-jiggle fix attached.


Thanks,


Matt


---
From: Matt Evans <matt@ozlabs.org>
Date: Wed, 14 Dec 2011 12:10:03 +1100
Subject: [PATCH] kvm tools: Fix build of util.c on 32bit machines

commit 378ee7e6dd301347c6bf2c740cb1fb40174bcb8b broke the -Werror build
on 32bit targets due to some variable typing in struct statfs.

Fixes the build.

Signed-off-by: Matt Evans <matt@ozlabs.org>
---
 tools/kvm/util/util.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/kvm/util/util.c b/tools/kvm/util/util.c
index ad5418e..00f7315 100644
--- a/tools/kvm/util/util.c
+++ b/tools/kvm/util/util.c
@@ -86,17 +86,19 @@ void *mmap_hugetlbfs(const char *htlbfs_path, u64 size)
 	int fd;
 	struct statfs sfs;
 	void *addr;
+	unsigned long blk_size;
 
 	if (statfs(htlbfs_path, &sfs) < 0)
 		die("Can't stat %s\n", htlbfs_path);
 
-	if (sfs.f_type != HUGETLBFS_MAGIC) {
+	if ((unsigned int)sfs.f_type != HUGETLBFS_MAGIC) {
 		die("%s is not hugetlbfs!\n", htlbfs_path);
 	}
 
-	if (sfs.f_bsize == 0 || (unsigned long)sfs.f_bsize > size) {
+	blk_size = (unsigned long)sfs.f_bsize;
+	if (sfs.f_bsize == 0 || blk_size > size) {
 		die("Can't use hugetlbfs pagesize %ld for mem size %lld\n",
-		    sfs.f_bsize, size);
+		    blk_size, size);
 	}
 
 	snprintf(mpath, PATH_MAX, "%s/kvmtoolXXXXXX", htlbfs_path);
-- 
1.7.0.4