Philippe, thanks for the fast review,
John, thanks for picking up this hot potato :-)
Sam
On Thu, Sep 26, 2019 at 10:16 PM Philippe Mathieu-Daudé philmd@redhat.com wrote:
On 9/26/19 9:09 PM, Philippe Mathieu-Daudé wrote:
On 9/26/19 8:26 PM, John Snow wrote:
On 9/26/19 5:57 AM, Philippe Mathieu-Daudé wrote:
Hi Sam,
On 9/25/19 1:06 PM, Sam Eiderman wrote:
From: Sam Eiderman shmuel.eiderman@oracle.com
Using fw_cfg, supply logical CHS values directly from QEMU to the
BIOS.
Non-standard logical geometries break under QEMU.
A virtual disk which contains an operating system which depends on logical geometries (consistent values being reported from BIOS INT13 AH=08) will most likely break under QEMU/SeaBIOS if it has
non-standard
logical geometries - for example 56 SPT (sectors per track). No matter what QEMU will report - SeaBIOS, for large enough disks -
will
use LBA translation, which will report 63 SPT instead.
In addition we cannot force SeaBIOS to rely on physical geometries at all. A virtio-blk-pci virtual disk with 255 phyiscal heads cannot report more than 16 physical heads when moved to an IDE controller, since the ATA spec allows a maximum of 16 heads - this is an artifact
of
virtualization.
By supplying the logical geometries directly we are able to support
such
"exotic" disks.
We serialize this information in a similar way to the "bootorder" interface. The new fw_cfg entry is "bios-geometry".
Reviewed-by: Karl Heubaum karl.heubaum@oracle.com Reviewed-by: Arbel Moshe arbel.moshe@oracle.com Signed-off-by: Sam Eiderman shmuel.eiderman@oracle.com
bootdevice.c | 32 ++++++++++++++++++++++++++++++++ hw/nvram/fw_cfg.c | 14 +++++++++++--- include/sysemu/sysemu.h | 1 + 3 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/bootdevice.c b/bootdevice.c index 2b12fb85a4..b034ad7bdc 100644 --- a/bootdevice.c +++ b/bootdevice.c @@ -405,3 +405,35 @@ void del_boot_device_lchs(DeviceState *dev,
const char *suffix)
} }}
+/* Serialized as: (device name\0 + lchs struct) x devices */ +char *get_boot_devices_lchs_list(size_t *size) +{
- FWLCHSEntry *i;
- size_t total = 0;
- char *list = NULL;
- QTAILQ_FOREACH(i, &fw_lchs, link) {
char *bootpath;char *chs_string;size_t len;bootpath = get_boot_device_path(i->dev, false, i->suffix);chs_string = g_strdup_printf("%s %" PRIu32 " %" PRIu32 " %"PRIu32,
bootpath, i->lcyls, i->lheads,i->lsecs);
Hmm maybe we can g_free(bootpath) directly here.
I think it's okay to do it at the bottom of the loop. No real benefit to being that eager to free resources in my mind. I expect setup at the top of a block and teardown at the bottom of a block.
Trying to do too much in the middle gets messy in my opinion, not that it seems to matter here.
No problem.
if (total) {list[total - 1] = '\n';}len = strlen(chs_string) + 1;list = g_realloc(list, total + len);memcpy(&list[total], chs_string, len);total += len;g_free(chs_string);g_free(bootpath);- }
- *size = total;
- return list;
+} diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 7dc3ac378e..18aff658c0 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -920,13 +920,21 @@ void *fw_cfg_modify_file(FWCfgState *s, const
char *filename,
static void fw_cfg_machine_reset(void *opaque) {
- MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
- FWCfgState *s = opaque; void *ptr; size_t len;
- FWCfgState *s = opaque;
- char *bootindex = get_boot_devices_list(&len);
- char *buf;
- ptr = fw_cfg_modify_file(s, "bootorder", (uint8_t *)bootindex,
len);
- buf = get_boot_devices_list(&len);
- ptr = fw_cfg_modify_file(s, "bootorder", (uint8_t *)buf, len); g_free(ptr);
- if (!mc->legacy_fw_cfg_order) {
buf = get_boot_devices_lchs_list(&len);ptr = fw_cfg_modify_file(s, "bios-geometry", (uint8_t *)buf,len);
OK. Can you add a test in tests/fw_cfg-test.c please?
:D
g_free(ptr);- }
}
static void fw_cfg_machine_ready(struct Notifier *n, void *data) diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h index 5bc5c79cbc..80c57fdc4e 100644 --- a/include/sysemu/sysemu.h +++ b/include/sysemu/sysemu.h @@ -106,6 +106,7 @@ void validate_bootdevices(const char *devices,
Error **errp);
void add_boot_device_lchs(DeviceState *dev, const char *suffix, uint32_t lcyls, uint32_t lheads, uint32_t
lsecs);
void del_boot_device_lchs(DeviceState *dev, const char *suffix); +char *get_boot_devices_lchs_list(size_t *size);
Please add some documentation. At least 'size' must be non-NULL.
Sure; but I wasn't going to gate on it because this series went unloved for so long. At this point, a follow-up patch is fine.
OK
Ideally you should add doc for the other functions added in 3/8 "bootdevice: Add interface to gather LCHS" too.
Same thing here.
John, what do you think about extracting the *boot_device* functions
out
of "sysemu.h"?
Potentially worthwhile; but not critical at the moment. The source tree is not the best-organized thing as-is and I don't think it's fair to hold this series up for much longer for nice-to-haves, ultimately.
More targeted improvements might avoid the "whose responsibility is it to stage this?" hot potato we played with this one; so I'd rather have smaller follow-up patches handled by the respective maintainers.
Sure, fair enough.
I forgot: Reviewed-by: Philippe Mathieu-Daudé philmd@redhat.com