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Re: pvgrub2 and old grub menu.lst
From: |
Andrey Borzenkov |
Subject: |
Re: pvgrub2 and old grub menu.lst |
Date: |
Wed, 2 Apr 2014 20:13:14 +0400 |
В Wed, 2 Apr 2014 14:29:50 +0400
Andrey Borzenkov <address@hidden> пишет:
> On Wed, Apr 2, 2014 at 12:43 PM, Michael Chang <address@hidden> wrote:
> > On Tue, Apr 01, 2014 at 08:06:44PM +0400, Andrey Borzenkov wrote:
> >> В Tue, 1 Apr 2014 15:46:22 +0800
> >> Michael Chang <address@hidden> пишет:
> >>
> >> > While trying to boot xen pv guest with old grub config (menu.lst),
> >> > the pvgrub2 loads it's menu successfully, but when you attemp to boot
> >> > the kernel it failed with the following message.
> >> >
> >> > error: couldn't load file /boot/vmlinuz-3.0.76-0.11-xen.
> >> > error: you need to load the kernel first.
> >> >
> >> > Press any key to continue..."
> >> >
> >> > The kernel is there and boots fine with pygrub.
> >> >
> >> > After some investigation, it boils down to the menu.lst has explicitly
> >> > set it's root device to (hd0,1) and therefore the root device is not
> >> > recognized by pvgrub2.
> >> >
> >> > title Xen -- SUSE Linux Enterprise Server 11 SP3 - 3.0.76-0.11
> >> > root (hd0,1)
> >> > kernel /boot/vmlinuz-3.0.76-0.11-xen root=/dev/xvda2 resume=/dev/xvda1
> >> > splash=silent showopts initrd /boot/initrd-3.0.76-0.11.xen
> >> >
> >> > I'd like to know whether old grub configuration is considered or planned
> >> > to work with pvgrub2 ? And is it a viable suggestion to have (hdX,Y) a
> >> > valid xen disk name because it's quite common in some existing configs ?
> >> >
> >>
> >> I believe this technically should work; but this needs someone who
> >> knows how Xen disks is mapped to hd number in legacy grub.
> >>
> >> It would be something like (completely untested)
> >
> > Thank you for the patch. I applied it and tried to test it. The
> > virtdisks[i].handle never matched with num as it's id of the disk (on
> > my system it is 51712).
> >
>
> As I said, completely untested :)
>
> > Please pardon my ignorant, can num be the index to the virtdisks array
> > to get the mapped xen disk ?
> >
>
> pv-grub additionally sorts by handle:
> http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=stubdom/grub/mini-os.c;h=9d4bcc76d5f3e9907889948ee0dcea32e19c185b;hb=HEAD#l73
>
> So to actually map pv-grub hdX we need to do the same.
Could you test patch below (compile-tested)?
From: Andrey Borzenkov <address@hidden>
Subject: [PATCH] accept also hdX as alias to native Xen disk name
To assign correct disk numbers, sort disks by increasing order of handle
value. This allows reusing legacy pv-grub menu.lst which is using hdX names.
Suggested-By: Michael Chang <address@hidden>
---
grub-core/disk/xen/xendisk.c | 45 +++++++++++++++++++++++++++++++++++---------
1 file changed, 36 insertions(+), 9 deletions(-)
diff --git a/grub-core/disk/xen/xendisk.c b/grub-core/disk/xen/xendisk.c
index 2b11c2a..b18a923 100644
--- a/grub-core/disk/xen/xendisk.c
+++ b/grub-core/disk/xen/xendisk.c
@@ -40,6 +40,7 @@ struct virtdisk
grub_xen_evtchn_t evtchn;
void *dma_page;
grub_xen_grant_t dma_grant;
+ struct virtdisk *compat_next;
};
#define xen_wmb() mb()
@@ -47,6 +48,7 @@ struct virtdisk
static struct virtdisk *virtdisks;
static grub_size_t vdiskcnt;
+struct virtdisk *compat_head;
static int
grub_virtdisk_iterate (grub_disk_dev_iterate_hook_t hook, void *hook_data,
@@ -66,20 +68,32 @@ grub_virtdisk_iterate (grub_disk_dev_iterate_hook_t hook,
void *hook_data,
static grub_err_t
grub_virtdisk_open (const char *name, grub_disk_t disk)
{
- grub_size_t i;
+ int i;
grub_uint32_t secsize;
char fdir[200];
char *buf;
+ int num = -1;
+ struct virtdisk *vd;
- for (i = 0; i < vdiskcnt; i++)
- if (grub_strcmp (name, virtdisks[i].fullname) == 0)
+ /* For compatibility with pv-grub legacy menu.lst accept hdX as disk name */
+ if (name[0] == 'h' && name[1] == 'd' && name[2])
+ {
+ num = grub_strtoul (name + 2, 0, 10);
+ if (grub_errno)
+ {
+ grub_errno = 0;
+ num = -1;
+ }
+ }
+ for (i = 0, vd = compat_head; vd; vd = vd->compat_next, i++)
+ if (i == num || grub_strcmp (name, vd->fullname) == 0)
break;
- if (i == vdiskcnt)
+ if (!vd)
return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "not a virtdisk");
- disk->data = &virtdisks[i];
- disk->id = i;
+ disk->data = vd;
+ disk->id = vd - virtdisks;
- grub_snprintf (fdir, sizeof (fdir), "%s/sectors", virtdisks[i].backend_dir);
+ grub_snprintf (fdir, sizeof (fdir), "%s/sectors", vd->backend_dir);
buf = grub_xenstore_get_file (fdir, NULL);
if (!buf)
return grub_errno;
@@ -87,8 +101,7 @@ grub_virtdisk_open (const char *name, grub_disk_t disk)
if (grub_errno)
return grub_errno;
- grub_snprintf (fdir, sizeof (fdir), "%s/sector-size",
- virtdisks[i].backend_dir);
+ grub_snprintf (fdir, sizeof (fdir), "%s/sector-size", vd->backend_dir);
buf = grub_xenstore_get_file (fdir, NULL);
if (!buf)
return grub_errno;
@@ -264,6 +277,7 @@ fill (const char *dir, void *data)
grub_err_t err;
void *buf;
struct evtchn_alloc_unbound alloc_unbound;
+ struct virtdisk **prev = &compat_head, *vd = compat_head;
/* Shouldn't happen unles some hotplug happened. */
if (vdiskcnt >= *ctr)
@@ -374,6 +388,19 @@ fill (const char *dir, void *data)
virtdisks[vdiskcnt].frontend_dir = grub_strdup (fdir);
+ /* For compatibility with pv-grub maintain linked list sorted by handle
+ value in increasing order. This allows mapping of (hdX) disk names
+ from legacy menu.lst */
+ while (vd)
+ {
+ if (vd->handle > virtdisks[vdiskcnt].handle)
+ break;
+ prev = &vd->compat_next;
+ vd = vd->compat_next;
+ }
+ virtdisks[vdiskcnt].compat_next = vd;
+ *prev = &virtdisks[vdiskcnt];
+
vdiskcnt++;
return 0;
--
tg: (4afd010..) e/xen/hdX-compat (depends on: master)