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Re: [Qemu-devel] [PATCH] qemu-xen: make use of xenstore relative paths
From: |
Anthony PERARD |
Subject: |
Re: [Qemu-devel] [PATCH] qemu-xen: make use of xenstore relative paths |
Date: |
Thu, 26 Sep 2013 17:46:31 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Sep 18, 2013 at 09:50:58PM +0200, Roger Pau Monne wrote:
> Qemu has several hardcoded xenstore paths that are only valid on Dom0.
> Attempts to launch a Qemu instance (to act as a userspace backend for
> PV disks) will fail because Qemu is not able to access those paths
> when running on a domain different than Dom0.
>
> Instead make the xenstore paths relative to the domain where Qemu is
> actually running.
>
> Signed-off-by: Roger Pau Monné <address@hidden>
> Cc: address@hidden
> Cc: Anthony PERARD <address@hidden>
> Cc: Stefano Stabellini <address@hidden>
This look fine. One issue with the patch: the file xen_backend.c have
been moved to hw/xen/xen_backend.c.
I've also tryied it in a stubdomain, and it does not boot anymore
because the qemu in the stubdom can not read the state. I have tried
again without the change in xen-all.c, and the stubdom does not complain
anymore. So in the change in xenstore_record_dm_state() needed as well?
> ---
> hw/xen_backend.c | 19 ++++++-------------
> xen-all.c | 2 +-
> 2 files changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/hw/xen_backend.c b/hw/xen_backend.c
> index 008cdb3..e220606 100644
> --- a/hw/xen_backend.c
> +++ b/hw/xen_backend.c
> @@ -205,7 +205,6 @@ static struct XenDevice *xen_be_get_xendev(const char
> *type, int dom, int dev,
> struct XenDevOps *ops)
> {
> struct XenDevice *xendev;
> - char *dom0;
>
> xendev = xen_be_find_xendev(type, dom, dev);
> if (xendev) {
> @@ -219,12 +218,10 @@ static struct XenDevice *xen_be_get_xendev(const char
> *type, int dom, int dev,
> xendev->dev = dev;
> xendev->ops = ops;
>
> - dom0 = xs_get_domain_path(xenstore, 0);
> - snprintf(xendev->be, sizeof(xendev->be), "%s/backend/%s/%d/%d",
> - dom0, xendev->type, xendev->dom, xendev->dev);
> + snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
> + xendev->type, xendev->dom, xendev->dev);
> snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
> xendev->type, xendev->dev);
> - free(dom0);
>
> xendev->debug = debug;
> xendev->local_port = -1;
> @@ -570,14 +567,12 @@ static int xenstore_scan(const char *type, int dom,
> struct XenDevOps *ops)
> {
> struct XenDevice *xendev;
> char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
> - char **dev = NULL, *dom0;
> + char **dev = NULL;
> unsigned int cdev, j;
>
> /* setup watch */
> - dom0 = xs_get_domain_path(xenstore, 0);
> snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
> - snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
> - free(dom0);
> + snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
> if (!xs_watch(xenstore, path, token)) {
> xen_be_printf(NULL, 0, "xen be: watching backend path (%s)
> failed\n", path);
> return -1;
> @@ -603,12 +598,10 @@ static void xenstore_update_be(char *watch, char *type,
> int dom,
> struct XenDevOps *ops)
> {
> struct XenDevice *xendev;
> - char path[XEN_BUFSIZE], *dom0, *bepath;
> + char path[XEN_BUFSIZE], *bepath;
> unsigned int len, dev;
>
> - dom0 = xs_get_domain_path(xenstore, 0);
> - len = snprintf(path, sizeof(path), "%s/backend/%s/%d", dom0, type, dom);
> - free(dom0);
> + len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
> if (strncmp(path, watch, len) != 0) {
> return;
> }
> diff --git a/xen-all.c b/xen-all.c
> index 15be8ed..99666f9 100644
> --- a/xen-all.c
> +++ b/xen-all.c
> @@ -967,7 +967,7 @@ static void xenstore_record_dm_state(struct xs_handle
> *xs, const char *state)
> exit(1);
> }
>
> - snprintf(path, sizeof (path), "/local/domain/0/device-model/%u/state",
> xen_domid);
> + snprintf(path, sizeof (path), "device-model/%u/state", xen_domid);
> if (!xs_write(xs, XBT_NULL, path, state, strlen(state))) {
> fprintf(stderr, "error recording dm state\n");
> exit(1);
> --
> 1.7.7.5 (Apple Git-26)
>
--
Anthony PERARD