On Thu, Feb 15, 2018 at 05:31:42PM -0500, Stephen John Smoogen wrote:> On 15 February 2018 at 17:19, Yves Bellefeuille <yan at storm.ca> wrote: > > I have a UEFI system, but I want to install CentOS on a MBR (not GPT) > > hard disk. > > > > The installation program keeps telling me that I must create an "EFI > > system partition on a GPT disk mounted at /boot/efi". > > > > I can't find a way to work around this. Is there a solution? > > > > If the installer is doing that then it usually means that the UEFI > firmware is either > a) not in BIOS compatibility mode > b) does not respond in a way that Linux detects or > c) the disk is larger than what BIOS compatibility mode will allow. > > Otherwise anaconda should default to MBR unless it finds the hardware > does not know how to deal with MBR. > > https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/installation_guide/chap-anaconda-boot-options >I had the same issue back when I installed 7.x on this box. I couldn't find a way around it, so I finally just went with the flow. I definitely DID have it in legacy mode, or at least the firmware's GUI said I did. -- ---- Fred Smith -- fredex at fcshome.stoneham.ma.us ----------------------------- "And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace. Of the increase of his government there will be no end. He will reign on David's throne and over his kingdom, establishing and upholding it with justice and righteousness from that time on and forever." ------------------------------- Isaiah 9:7 (niv) ------------------------------
On 15 February 2018 at 18:05, Fred Smith <fredex at fcshome.stoneham.ma.us> wrote:> On Thu, Feb 15, 2018 at 05:31:42PM -0500, Stephen John Smoogen wrote: >> On 15 February 2018 at 17:19, Yves Bellefeuille <yan at storm.ca> wrote: >> > I have a UEFI system, but I want to install CentOS on a MBR (not GPT) >> > hard disk. >> > >> > The installation program keeps telling me that I must create an "EFI >> > system partition on a GPT disk mounted at /boot/efi". >> > >> > I can't find a way to work around this. Is there a solution? >> > >> >> If the installer is doing that then it usually means that the UEFI >> firmware is either >> a) not in BIOS compatibility mode >> b) does not respond in a way that Linux detects or >> c) the disk is larger than what BIOS compatibility mode will allow. >> >> Otherwise anaconda should default to MBR unless it finds the hardware >> does not know how to deal with MBR. >> >> https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/installation_guide/chap-anaconda-boot-options >> > > I had the same issue back when I installed 7.x on this box. I couldn't > find a way around it, so I finally just went with the flow. > > I definitely DID have it in legacy mode, or at least the firmware's > GUI said I did.OK I am going with documentation not being right and/or I have been very lucky with my installs. The only other thing I can think of is that the disk was already formatted to GPT. In that case it has to be EFI. [I had a disk which was GPT partitioned and removing that was quite a challenge as I had done a 'dd if=/dev/zero of=/dev/sda bs=512 count=10' and it still kept coming up as GPT. I believe I had to run a different disk command to really clean it.]> > -- > ---- Fred Smith -- fredex at fcshome.stoneham.ma.us ----------------------------- > "And he will be called Wonderful Counselor, Mighty God, Everlasting Father, > Prince of Peace. Of the increase of his government there will be no end. He > will reign on David's throne and over his kingdom, establishing and upholding > it with justice and righteousness from that time on and forever." > ------------------------------- Isaiah 9:7 (niv) ------------------------------ > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos-- Stephen J Smoogen.
Stephen John Smoogen <smooge at gmail.com> wrote:> OK I am going with documentation not being right and/or I have been > very lucky with my installs.If you read https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/installation_guide/sect-disk-partitioning-setup-x86#sect-bootloader-mbr-gpt-x86 carefully, it seems to say that if you have UEFI and an MBR hard disk that already has partitions, you must reformat it to GPT. The documentation seems to say that Anaconda will use MBR only if the disk is the right size (fewer than 2^32 sectors) *and* has no partition. -- Yves Bellefeuille <yan at storm.ca>
On Thu, Feb 15, 2018, 4:18 PM Stephen John Smoogen <smooge at gmail.com> wrote:> > The only other thing I can think of is that the disk was already > formatted to GPT. In that case it has to be EFI. [I had a disk which > was GPT partitioned and removing that was quite a challenge as I had > done a 'dd if=/dev/zero of=/dev/sda bs=512 count=10' and it still kept > coming up as GPT. I believe I had to run a different disk command to > really clean it.] >GPT has primary login at drive start, and backup location at drive end. To remove it requires wipefs -a /dev/ and it will remove the signature found in both primary and backup. Chris Murphy
On Thu, Feb 15, 2018 at 5:18 PM, Stephen John Smoogen <smooge at gmail.com> wrote:> The only other thing I can think of is that the disk was already > formatted to GPT. In that case it has to be EFI. [I had a disk which > was GPT partitioned and removing that was quite a challenge as I had > done a 'dd if=/dev/zero of=/dev/sda bs=512 count=10' and it still kept > coming up as GPT. I believe I had to run a different disk command to > really clean it.] >That didn't get rid of it because GPT keeps a secondary copy of header info at the end of the drive. To really get rid of it use a tool that wipes GPT headers, or a full wipe of the drive. gdisk has eXpert mode that has an option (z) to wipe GPT headers. https://en.wikipedia.org/wiki/GUID_Partition_Table#/media/File:GUID_Partition_Table_Scheme.svg