[Xen-devel] [PATCH] Fix change of CDROM for block-configure command

["Kasai Takanori" <kasai.takanori@xxxxxxxxxxxxxx>]

Hi All,

We contributed the problem when CD-ROM was changed as follows.
There was especially no comment though we confirmed the correction method.
Therefore, the patch that corrects these problems is contributed.

Signed-off-by: Takanori Kasai <kasai.takanori@xxxxxxxxxxxxxx>

Best Regards,

---
Takanori Kasai


----- Original Message ----- 
From: "Kasai Takanori" <kasai.takanori@xxxxxxxxxxxxxx>
To: "xen-devel" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Sent: Thursday, June 14, 2007 7:30 PM
Subject: [Xen-devel] About change of CDROM


> Hi All,
>
> We tested xm block-configure command.
> Because when the domain image is made, we install it from multiple CDROM.
>
> The procedure of the installation is as follows.
> 1) The HVM domain is started with the CDROM device.
> 　・configuration file :
>   　disk = [
> 'file:/xen/test/install-test.img,hda,w','phy:/dev/cdrom,hdc:cdrom,r' ]
>   　boot="d"
> 2) When the installation from CDROM of the first piece is completed, CDROM is
> exchanged.
> 3) The exchange of CD-ROM is set by the xm block-configure command.
>  # xm block-configure <DomID> phy:/dev/cdrom hdc:cdrom r
> 4) The installation from CDROM of the second piece is continued.
>
> However, there are two problems in this procedure.
> 1) It takes time to recognize the exchange of CDROM.
> 2) Even if the same device is specified, it is not recognized.
>
> We investigated these problems.
>
> 1) It takes time to recognize the exchange of CDROM.
>
> The problem that it takes time for recognition is to wait intentionally on the
> qemu-dm side.
> ・tools/ioemu/xenstore.c
> 314 void xenstore_process_event(void *opaque)
> 315 {
> ...
> 343     if (image[0]) {
> 344         media_filename[hd_index] = strdup(image);
> 345         xenstore_check_new_media_present(5000);     << This
> 346     }
>
> The processing recognized after it waits for five seconds is executed.
> We think that this waiting is unnecessary after exchanges CDROM.
>
> Why do you wait for five seconds before CDROM recognizes it?
> If it is unnecessary, we want to correct not to wait.
>
> 2) Even if the same device is specified, it is not recognized.
>
> Therefore, we allocated it in other devices once.
> # xm block-configure <DomID> phy:/dev/null hdc:cdrom r
> # xm block-configure <DomID> phy:/dev/cdrom hdc:cdrom r
>
> It is made not to recognize that the same device is specified in qemu-dm.
> ・tools/ioemu/xenstore.c
> 314 void xenstore_process_event(void *opaque)
> 315 {
> ...
> 332     image = xs_read(xsh, XBT_NULL, vec[XS_WATCH_PATH], &len);
> 333     if (image == NULL || !strcmp(image, bs_table[hd_index]->filename))  <<
> This
> 334         goto out;  /* gone or identical */
>
> It doesn't operate because it becomes naturally the same name
> when physics CDROM is allocated.
> Even if the name is the same, the content might be not same.
> Only when CDROM is exchanged, it is executed.
>
> When the same device is specified, should we check it?
> We want to correct not to check it.
>
>
> We have confirmed these problems are canceled by the appended patch.
>
> Best Regards,
>
> --
> Takanori Kasai

Attachment: ioemu-nocheck-change.patch
Description: Binary data

Attachment: ioemu-nowait-change.patch
Description: Binary data

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