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Recovering UEFI boot entries after clear CMOS



 
 
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  #1  
Old April 25th 17, 12:19 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mr. Man-wai Chang
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Posts: 1,373
Default Recovering UEFI boot entries after clear CMOS


How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


--
@[email protected] Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
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  #2  
Old April 25th 17, 05:44 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mark Lloyd[_2_]
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Posts: 906
Default Recovering UEFI boot entries after clear CMOS

On 04/25/2017 06:19 AM, Mr. Man-wai Chang wrote:

How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


What did you change in setup? Boot order? Secure boot?

--
Mark Lloyd
http://notstupid.us/

"If we should put god in the Constitution there would be no room left
for man." [Robert G. Ingersoll]
  #3  
Old April 25th 17, 05:50 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mr. Man-wai Chang
external usenet poster
 
Posts: 1,373
Default Recovering UEFI boot entries after clear CMOS

On 26/4/2017 12:44 AM, Mark Lloyd wrote:
On 04/25/2017 06:19 AM, Mr. Man-wai Chang wrote:

How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


What did you change in setup? Boot order? Secure boot?


I just wanna find out whether the UEFI boot entry would stay in the CMOS
after I clear the CMOS. Anyone tested it before?

Ib the case of MBR boot, no boot entry was stored in the CMOS, so
clearing the CMOS would not affect the booting process.


--
@[email protected] Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
  #4  
Old April 26th 17, 01:41 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mark Lloyd[_2_]
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Posts: 906
Default Recovering UEFI boot entries after clear CMOS

On 04/25/2017 11:50 AM, Mr. Man-wai Chang wrote:
On 26/4/2017 12:44 AM, Mark Lloyd wrote:
On 04/25/2017 06:19 AM, Mr. Man-wai Chang wrote:

How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


What did you change in setup? Boot order? Secure boot?


I just wanna find out whether the UEFI boot entry would stay in the CMOS
after I clear the CMOS. Anyone tested it before?


I would expect that UEFI reads the GPT boot information from disk, just
like it reads the MBR boot information. In that case, a CMOS reset would
have no effect.

If it did, you'll still be able to boot since it'll give the disk drive
name.

Ib the case of MBR boot, no boot entry was stored in the CMOS, so
clearing the CMOS would not affect the booting process.


--
Mark Lloyd
http://notstupid.us/

"If we should put god in the Constitution there would be no room left
for man." [Robert G. Ingersoll]
  #5  
Old April 26th 17, 05:12 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Tim[_8_]
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Posts: 141
Default Recovering UEFI boot entries after clear CMOS

"Mr. Man-wai Chang" wrote in newsdnuj3$c5u$1
@dont-email.me:

On 26/4/2017 12:44 AM, Mark Lloyd wrote:
On 04/25/2017 06:19 AM, Mr. Man-wai Chang wrote:

How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


What did you change in setup? Boot order? Secure boot?


I just wanna find out whether the UEFI boot entry would stay in the CMOS
after I clear the CMOS. Anyone tested it before?

Ib the case of MBR boot, no boot entry was stored in the CMOS, so
clearing the CMOS would not affect the booting process.


I believe that after the CMOS is cleared, the system will start scanning
the hard/ssd drives starting at disk 0 until it finds a valid boot block.

You should be able to enter the UEFI Bios after clearing the CMOS and
select which drive to boot from. As part of the boot process the BIOS scans
all of the drives to make a list of what is there.

I keep a little table of all of the physical drives and which partitions
with their sizes are on which physical drive. That way I always have at
hand which drive/partition I was using as the system drive.
  #6  
Old April 26th 17, 08:58 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mr. Man-wai Chang
external usenet poster
 
Posts: 1,373
Default Recovering UEFI boot entries after clear CMOS

On 26/4/2017 12:12 PM, Tim wrote:
I believe that after the CMOS is cleared, the system will start scanning
the hard/ssd drives starting at disk 0 until it finds a valid boot block.

You should be able to enter the UEFI Bios after clearing the CMOS and
select which drive to boot from. As part of the boot process the BIOS scans
all of the drives to make a list of what is there.


Did you test this?

--
@[email protected] Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
  #7  
Old April 26th 17, 10:19 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Gianni Turri
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Posts: 45
Default Recovering UEFI boot entries after clear CMOS

On Tue, 25 Apr 2017 19:19:31 +0800, "Mr. Man-wai Chang"
wrote:


How do you do that easily? Must I always keep a recovery disc ready? If
so, wouldn't it make things more complex than MBR boot?

The old MBR method can always boot even after a CMOS reset.


In my experience a CMOS reset don't touch your disks.

Eventually you need to set the BIOS to act as UEFI in case it
defaulted to Legacy.

Disable Legacy Boot Mode and Enable UEFI
https://neosmart.net/wiki/enable-uefi-boot/

--
Gianni
  #8  
Old April 26th 17, 10:42 AM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mr. Man-wai Chang
external usenet poster
 
Posts: 1,373
Default Recovering UEFI boot entries after clear CMOS

On 26/4/2017 5:19 PM, Gianni Turri wrote:

In my experience a CMOS reset don't touch your disks.


Not talking about modifying the disk, but the UEFI boot entry. Is the
UEFI boot entry "Windows Boot Manager" stored in the hard disk or CMOS?

--
@[email protected] Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
  #9  
Old April 26th 17, 12:55 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Gianni Turri
external usenet poster
 
Posts: 45
Default Recovering UEFI boot entries after clear CMOS

On Wed, 26 Apr 2017 17:42:12 +0800, "Mr. Man-wai Chang"
wrote:

On 26/4/2017 5:19 PM, Gianni Turri wrote:

In my experience a CMOS reset don't touch your disks.


Not talking about modifying the disk, but the UEFI boot entry. Is the
UEFI boot entry "Windows Boot Manager" stored in the hard disk or CMOS?


Windows Boot Manager is stored on your disk.

Where is the BIOS stored?
https://superuser.com/questions/7072...he-bios-stored
  #10  
Old April 26th 17, 01:51 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Gianni Turri
external usenet poster
 
Posts: 45
Default Recovering UEFI boot entries after clear CMOS

On Wed, 26 Apr 2017 13:55:26 +0200, Gianni Turri
wrote:

On Wed, 26 Apr 2017 17:42:12 +0800, "Mr. Man-wai Chang"
wrote:

On 26/4/2017 5:19 PM, Gianni Turri wrote:

In my experience a CMOS reset don't touch your disks.


Not talking about modifying the disk, but the UEFI boot entry. Is the
UEFI boot entry "Windows Boot Manager" stored in the hard disk or CMOS?


Windows Boot Manager is stored on your disk.

Where is the BIOS stored?
https://superuser.com/questions/7072...he-bios-stored


More on this topic ...

UEFI boot: how does that actually work, then?
https://www.happyassassin.net/2014/0...lly-work-then/

--
Gianni
  #11  
Old April 26th 17, 02:42 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Mr. Man-wai Chang
external usenet poster
 
Posts: 1,373
Default Recovering UEFI boot entries after clear CMOS

On 26/4/2017 8:51 PM, Gianni Turri wrote:

Windows Boot Manager is stored on your disk.

Where is the BIOS stored?
https://superuser.com/questions/7072...he-bios-stored


More on this topic ...

UEFI boot: how does that actually work, then?
https://www.happyassassin.net/2014/0...lly-work-then/


Thanks... reading them.

--
@[email protected] Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
  #12  
Old April 26th 17, 09:23 PM posted to alt.comp.os.windows-10,alt.comp.os.windows-8,alt.windows7.general
Tim[_8_]
external usenet poster
 
Posts: 141
Default Recovering UEFI boot entries after clear CMOS

"Mr. Man-wai Chang" wrote in
news
On 26/4/2017 12:12 PM, Tim wrote:
I believe that after the CMOS is cleared, the system will start
scanning the hard/ssd drives starting at disk 0 until it finds a
valid boot block.

You should be able to enter the UEFI Bios after clearing the CMOS and
select which drive to boot from. As part of the boot process the BIOS
scans all of the drives to make a list of what is there.


Did you test this?

No, I haven't actually cleared my CMOS to see what happens, but my UEFI
Bios shows me a list of my hard drives identified by manufacturer and model
number, and where else would it get that info except by scanning all of the
possible connections and pulling in the ID stored in every hard drive.

I do know from experiece that the Bios will scan all of the drives for a
boot sector. My system drive/disk (an SSD with nothing else on it but
Windows) decided to die on me right in the middle of upgrading to Win 10.
When I rebooted it found my online backup of that drive and booted from
that with no imput from me.
  #13  
Old April 27th 17, 03:13 PM posted to alt.comp.os.windows-8
philo
external usenet poster
 
Posts: 4,592
Default Recovering UEFI boot entries after clear CMOS

On 04/26/2017 03:23 PM, Tim wrote:
"Mr. Man-wai Chang" wrote in
news
On 26/4/2017 12:12 PM, Tim wrote:
I believe that after the CMOS is cleared, the system will start
scanning the hard/ssd drives starting at disk 0 until it finds a
valid boot block.

You should be able to enter the UEFI Bios after clearing the CMOS and
select which drive to boot from. As part of the boot process the BIOS
scans all of the drives to make a list of what is there.


Did you test this?

No, I haven't actually cleared my CMOS to see what happens, but my UEFI
Bios shows me a list of my hard drives identified by manufacturer and model
number, and where else would it get that info except by scanning all of the
possible connections and pulling in the ID stored in every hard drive.

I do know from experiece that the Bios will scan all of the drives for a
boot sector. My system drive/disk (an SSD with nothing else on it but
Windows) decided to die on me right in the middle of upgrading to Win 10.
When I rebooted it found my online backup of that drive and booted from
that with no imput from me.




I just built a new machine and had to make one change in the bios to
enable "legacy" in order to get the system to boot.

I would imagine that if I cleared CMOS I'd have to make that same change .

In other words best to note any changes before clearing CMOS

Whenever I work on a machine if there is anything of significance I need
to do I make a note of it and tape it to the back of the machine
 




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